Ultrasonic surgical instruments

ABSTRACT

In one general aspect, various embodiments are directed to an ultrasonic surgical instrument that comprises a transducer configured to produce vibrations along a longitudinal axis at a predetermined frequency. In various embodiments, an ultrasonic blade extends along the longitudinal axis and is coupled to the transducer. In various embodiments, the ultrasonic blade includes a body having a proximal end and a distal end, wherein the distal end is movable relative to the longitudinal axis by the vibrations produced by the transducer.

BACKGROUND

The present invention relates, in general, to ultrasonic surgicalinstruments. Ultrasonic instruments, including both hollow core andsolid core instruments, are used for the safe and effective treatment ofmany medical conditions. Ultrasonic instruments, and particularly solidcore ultrasonic instruments, are advantageous because they may be usedto cut and/or coagulate organic tissue using energy in the form ofmechanical vibrations transmitted to a surgical end effector atultrasonic frequencies. Ultrasonic vibrations, when transmitted toorganic tissue at suitable energy levels and using a suitable endeffector, may be used to cut, dissect, elevate or cauterize tissue or toseparate muscle tissue from bone. Ultrasonic instruments utilizing solidcore technology are particularly advantageous because of the amount ofultrasonic energy that may be transmitted from the ultrasonictransducer, through a waveguide, and to the surgical end effector. Suchinstruments may be used for open procedures or minimally invasiveprocedures, such as endoscopic or laparoscopic procedures, wherein theend effector is passed through a trocar to reach the surgical site.

Activating or exciting the end effector (e.g., cutting blade) of suchinstruments at ultrasonic frequencies induces longitudinal vibratorymovement that generates localized heat within adjacent tissue. Becauseof the nature of ultrasonic instruments, a particular ultrasonicallyactuated end effector may be designed to perform numerous functions,including, for example, cutting and coagulation. Ultrasonic vibration isinduced in the surgical end effector by electrically exciting atransducer, for example. The transducer may be constructed of one ormore piezoelectric or magnetostrictive elements in the instrument handpiece. Vibrations generated by the transducer are transmitted to thesurgical end effector via an ultrasonic waveguide extending from thetransducer to the surgical end effector. The waveguide and end effectorare designed to resonate at the same frequency as the transducer.Therefore, when an end effector is attached to a transducer, the overallsystem frequency is the same frequency as the transducer itself.

The amplitude of the longitudinal ultrasonic vibration at the tip, d, ofthe end effector behaves as a simple sinusoid at the resonant frequencyas given by:

d=A sin(ωt)

where:

ω=the radian frequency which equals 2π times the cyclic frequency, f;and

A=the zero-to-peak amplitude.

The longitudinal excursion of the end effector tip is defined as thepeak-to-peak (p-t-p) amplitude, which is just twice the amplitude of thesine wave or 2A. Often, the end effector can comprise a blade which,owing to the longitudinal excursion, can cut and/or coagulate tissue.U.S. Pat. No. 6,283,981, which issued on Sep. 4, 2001 and is entitledMETHOD OF BALANCING ASYMMETRIC ULTRASONIC SURGICAL BLADES; U.S. Pat. No.6,309,400, which issued on Oct. 30, 2001 and is entitled CURVEDULTRASONIC BLADE HAVING A TRAPEZOIDAL CROSS SECTION; and U.S. Pat. No.6,436,115, which issued on Aug. 20, 2002 and is entitled BALANCEDULTRASONIC BLADE INCLUDING A PLURALITY OF BALANCE ASYMMETRIES, theentire disclosures of which are hereby incorporated by reference herein,disclose various ultrasonic surgical instruments.

SUMMARY

In one general aspect, various embodiments are directed to an ultrasonicsurgical instrument that comprises a transducer configured to producevibrations along a longitudinal axis at a predetermined frequency. Invarious embodiments, an ultrasonic blade extends along the longitudinalaxis and is coupled to the transducer. In various embodiments, theultrasonic blade includes a body having a proximal end and a distal end,wherein the distal end is movable relative to the longitudinal axis bythe vibrations produced by the transducer.

FIGURES

The features of various embodiments are set forth with particularity inthe appended claims. The various embodiments, however, both as toorganization and methods of operation, together with further objects andadvantages thereof, may best be understood by reference to the followingdescription, taken in conjunction with the accompanying drawings asfollows.

FIG. 1 illustrates an embodiment of an ultrasonic surgical instrumentsystem.

FIG. 2 illustrates an embodiment of a connection union/joint for anultrasonic instrument.

FIG. 3 is a schematic of an end effector and a wave guide of anultrasonic surgical instrument and a representative longitudinal strainpattern and longitudinal stress pattern developed within the wave guideand end effector.

FIG. 4 is a schematic of a transducer of an ultrasonic surgicalinstrument and a representative longitudinal strain pattern andlongitudinal stress pattern developed within the transducer.

FIG. 5 is a schematic of the end effector and wave guide illustrated inFIG. 3 and a representative longitudinal displacement pattern developedwithin the wave guide and end effector.

FIG. 6 is a schematic of the transducer illustrated in FIG. 4 and arepresentative longitudinal displacement pattern developed within thetransducer.

FIG. 7 is a schematic of a transducer of an ultrasonic surgicalinstrument in accordance with at least one embodiment and arepresentative longitudinal strain pattern and a representativelongitudinal stress pattern developed within the transducer.

FIG. 8 illustrates an embodiment of a transducer comprisingpiezoelectric elements having different thicknesses.

FIG. 9 illustrates a second embodiment of a transducer comprisingpiezoelectric elements having different thicknesses.

FIG. 10 illustrates a third embodiment of a transducer comprisingpiezoelectric elements having different thicknesses.

FIG. 11 illustrates a fourth embodiment of a transducer comprisingpiezoelectric elements having different thicknesses.

FIG. 12 illustrates a fifth embodiment of a transducer comprisingpiezoelectric elements having different thicknesses.

FIG. 13 illustrates a sixth embodiment of a transducer comprisingpiezoelectric elements having different thicknesses.

FIG. 14 is a schematic of the work profiles that can be produced by thetransducer of FIG. 8 and the transducer of FIG. 11.

FIG. 15 illustrates an embodiment of a transducer comprisingpiezoelectric elements having different diameters.

FIG. 16 illustrates a second embodiment of a transducer comprisingpiezoelectric elements having different diameters.

FIG. 16A illustrates a third embodiment of a transducer comprisingpiezoelectric elements having different diameters.

FIG. 17 illustrates an embodiment of a transducer comprisingpiezoelectric elements and deflectable straps configured to cool thepiezoelectric elements.

FIG. 18 illustrates the deflectable straps of FIG. 17 being deflected byvibrations produced by the piezoelectric elements.

FIG. 19 illustrates an embodiment of a transducer comprisingpiezoelectric elements, deflectable straps configured to cool thepiezoelectric elements, and a plurality of masses mounted to thedeflectable straps.

FIG. 20 illustrates an embodiment of a wave guide, an end effector, asheath, and flexible membranes mounted to the wave guide and the sheathconfigured to displace air surrounding the wave guide and end effectorwhen the wave guide and end effector are vibrated.

FIG. 21 is an end view of the arrangement of FIG. 20.

FIG. 22A illustrates an embodiment of a transducer having a firstarrangement of piezoelectric elements.

FIG. 22B illustrates the transducer of FIG. 22A having a secondarrangement of piezoelectric elements.

FIG. 23A illustrates an embodiment of a transducer having a firstarrangement of piezoelectric elements.

FIG. 23B illustrates the transducer of FIG. 23A having a secondarrangement of piezoelectric elements.

FIG. 24 illustrates an embodiment of a transducer movably adjustablerelative to a wave guide.

FIG. 25 illustrates a kit for an ultrasonic surgical instrumentcomprising a plurality of wave guides and end effectors.

FIG. 26 illustrates an embodiment of an ultrasonic surgical instrument.

FIG. 27 illustrates a handle of an ultrasonic surgical instrument and aproximal portion of a wave guide, wherein the handle comprises aflexible housing.

FIG. 28 illustrates the handle of FIG. 27 in a flexed condition.

FIG. 29 illustrates an end view of the handle of FIG. 27 in an unflexedcondition.

FIG. 30 illustrates an end view of the handle of FIG. 27 in a flexedcondition.

FIG. 31 illustrates an embodiment of a surgical instrument comprising aplurality of transducers.

FIG. 32 illustrates a second embodiment of a surgical instrumentcomprising a plurality of transducers.

FIG. 33 illustrates an embodiment of an integral wave guide and endeffector.

FIG. 34 illustrates an embodiment of a transducer comprisingpiezoelectric elements assembled directly to a wave guide.

FIG. 35 illustrates an embodiment of a piezoelectric element andelectrodes mounted thereto, wherein the electrodes comprise tabsextending therefrom.

FIG. 36 illustrates a transducer stack comprising a plurality of thepiezoelectric elements of FIG. 35.

FIG. 37 illustrates an embodiment of a piezoelectric element andelectrodes mounted thereto.

FIG. 38 illustrates a transducer stack comprising a plurality of thepiezoelectric elements of FIG. 37.

FIG. 39 illustrates an end view of a transducer stack comprisingpiezoelectric elements, electrodes positioned intermediate thepiezoelectric elements, and connecting electrodes operably connectingthe intermediate electrodes.

FIG. 40 illustrates a transducer stack comprising a plurality ofpiezoelectric elements having a plurality of notches therein andconnecting electrodes extending through the notches.

FIG. 41 illustrates an end view of the transducer stack of FIG. 40.

FIG. 42 illustrates a transducer stack comprising a plurality ofpiezoelectric elements having a plurality of flat surfaces and aplurality of connecting electrodes.

FIG. 43 illustrates an end view of the transducer stack of FIG. 42.

FIG. 44 illustrates a transducer stack comprising a plurality ofpiezoelectric elements having a plurality of indexing featuresconfigured to assure the proper alignment of the piezoelectric elements.

FIG. 45 is a schematic illustrating how the indexing features of thepiezoelectric elements of FIG. 44 can prevent misalignment between thepiezoelectric elements.

FIG. 46 illustrates an embodiment of a transducer stack and an enclosuresurrounding the transducer stack.

FIG. 47 illustrates the enclosure of FIG. 46 in a ruptured condition anda material at least partially surrounding the transducer stack.

FIG. 48 illustrates a second embodiment of a transducer stack and anenclosure surrounding the transducer stack.

DESCRIPTION

Before explaining various embodiments in detail, it should be noted thatsuch embodiments are not limited in their application or use to thedetails of construction and arrangement of parts illustrated in theaccompanying drawings and description. The illustrative embodiments maybe implemented or incorporated in other embodiments, variations andmodifications, and may be practiced or carried out in various ways. Forexample, the surgical instruments disclosed below are illustrative onlyand not meant to limit the scope or application thereof. Furthermore,unless otherwise indicated, the terms and expressions employed hereinhave been chosen for the purpose of describing the illustrativeembodiments for the convenience of the reader and are not to limit thescope thereof.

Certain exemplary embodiments will now be described to provide anoverall understanding of the principles of the structure, function,manufacture, and use of the devices and methods disclosed herein. One ormore examples of these embodiments are illustrated in the accompanyingdrawings. Those of ordinary skill in the art will understand that thedevices and methods specifically described herein and illustrated in theaccompanying drawings are non-limiting exemplary embodiments and thatthe scope of the various embodiments is defined solely by the claims.The features illustrated or described in connection with one exemplaryembodiment may be combined with the features of other embodiments. Suchmodifications and variations are intended to be included within thescope of the claims.

Various embodiments described herein relate, in general, to ultrasonicsurgical instruments and blades for use therewith. Examples ofultrasonic surgical instruments and blades are disclosed in U.S. Pat.Nos. 5,322,055; 5,954,736; 6,309,400; 6,278,218; 6,283,981; and6,325,811, wherein the entire disclosures of which are incorporated byreference herein. Also incorporated by reference in its entirety iscommonly-owned, co-pending U.S. patent application Ser. No. 11/726,625,entitled ULTRASONIC SURGICAL INSTRUMENTS, filed on Mar. 22, 2007. Thedisclosures of the following commonly-owned, contemporaneously-filedUnited States patent applications are incorporated herein by referencein their entirety:

(1) U.S. patent application Ser. No. ______, entitled ULTRASONICSURGICAL INSTRUMENTS, Attorney Docket No. END6495USNP/080597;

(2) U.S. patent application Ser. No. ______, entitled ULTRASONICSURGICAL INSTRUMENTS, Attorney Docket No. END6495USNP2/080600; and

(4) U.S. patent application Ser. No. ______, entitled ULTRASONICSURGICAL INSTRUMENTS, Attorney Docket No. END6495USNP3/080601.

An ultrasonic instrument and blade according to various embodiments canbe of particular benefit, among others, in orthopedic procedures whereit is desirable to remove cortical bone and/or tissue while controllingbleeding. Due to its cutting and coagulation characteristics, a blade ofan ultrasonic surgical instrument may be useful for general soft tissuecutting and coagulation. In certain circumstances, a blade according tovarious embodiments may be useful to simultaneously cut andhemostatically seal or cauterize tissue. A blade may be straight orcurved, and useful for either open or laparoscopic applications. A bladeaccording to various embodiments may be useful in spine surgery,especially to assist in posterior access in removing muscle from bone.

FIG. 1 illustrates one embodiment of an ultrasonic system 10. Oneembodiment of the ultrasonic system 10 comprises an ultrasonic signalgenerator 12 coupled to an ultrasonic transducer 14, a hand pieceassembly 60 comprising a hand piece housing 16, and an end effector 50.The ultrasonic transducer 14, which is known as a “Langevin stack”,generally includes a transduction portion 18, a first resonator orend-bell 20, and a second resonator or fore-bell 22, and ancillarycomponents. In various embodiments, the ultrasonic transducer 14 ispreferably an integral number of one-half system wavelengths (nλ/2) inlength as will be described in more detail below. An acoustic assembly24 can include the ultrasonic transducer 14, a mount 26, a velocitytransformer 28, and a surface 30.

It will be appreciated that the terms “proximal” and “distal” are usedherein with reference to a clinician gripping the hand piece assembly60. Thus, the end effector 50 is distal with respect to the moreproximal hand piece assembly 60. It will be further appreciated that,for convenience and clarity, spatial terms such as “top” and “bottom”also are used herein with respect to the clinician gripping the handpiece assembly 60. However, surgical instruments are used in manyorientations and positions, and these terms are not intended to belimiting and absolute.

The distal end of the end-bell 20 is connected to the proximal end ofthe transduction portion 18, and the proximal end of the fore-bell 22 isconnected to the distal end of the transduction portion 18. Thefore-bell 22 and the end-bell 20 have a length determined by a number ofvariables, including the thickness of the transduction portion 18, thedensity and modulus of elasticity of the material used to manufacturethe end-bell 20 and the fore-bell 22, and the resonant frequency of theultrasonic transducer 14. The fore-bell 22 may be tapered inwardly fromits proximal end to its distal end to amplify the ultrasonic vibrationamplitude of the velocity transformer 28, or, alternately, fore-bell 22may have no amplification.

Referring again to FIG. 1, end-bell 20 can include a threaded memberextending therefrom which can be configured to be threadably engagedwith a threaded aperture in fore-bell 22. In various embodiments,piezoelectric elements, such as piezoelectric elements 32, for example,can be compressed between end-bell 20 and fore-bell 22 when end-bell 20and fore-bell 22 are assembled together. Piezoelectric elements 32 maybe fabricated from any suitable material, such as, for example, leadzirconate-titanate, lead meta-niobate, lead titanate, and/or anysuitable piezoelectric crystal material, for example.

In various embodiments, as discussed in greater detail below, transducer14 can further comprise electrodes, such as positive electrodes 34 andnegative electrodes 36, for example, which can be configured to create avoltage potential across one or more piezoelectric elements 32. Each ofthe positive electrodes 34, negative electrodes 36, and thepiezoelectric elements 32 can comprise a bore extending through thecenter which can be configured to receive the threaded member ofend-bell 20. In various embodiments, the positive and negativeelectrodes 34 and 36 are electrically coupled to wires 38 and 40,respectively, wherein the wires 38 and 40 can be encased within a cable42 and electrically connectable to the ultrasonic signal generator 12 ofthe ultrasonic system 10.

In various embodiments, the ultrasonic transducer 14 of the acousticassembly 24 converts the electrical signal from the ultrasonic signalgenerator 12 into mechanical energy that results in primarilylongitudinal vibratory motion of the ultrasonic transducer 24 and theend effector 50 at ultrasonic frequencies. A suitable generator isavailable as model number GEN01, from Ethicon Endo-Surgery, Inc.,Cincinnati, Ohio. When the acoustic assembly 24 is energized, avibratory motion standing wave is generated through the acousticassembly 24. A suitable vibrational frequency range may be about 20 Hzto 120 kHz and a well-suited vibrational frequency range may be about30-70 kHz and one example operational vibrational frequency may beapproximately 55.5 kHz.

The amplitude of the vibratory motion at any point along the acousticassembly 24 may depend upon the location along the acoustic assembly 24at which the vibratory motion is measured. A minimum or zero crossing inthe vibratory motion standing wave is generally referred to as a node(i.e., where motion is usually minimal), and an absolute value maximumor peak in the standing wave is generally referred to as an anti-node(i.e., where motion is usually maximal). The distance between ananti-node and its nearest node is one-quarter wavelength (λ/4).

As outlined above, the wires 38 and 40 transmit an electrical signalfrom the ultrasonic signal generator 12 to the positive electrodes 34and the negative electrodes 36. The piezoelectric elements 32 areenergized by the electrical signal supplied from the ultrasonic signalgenerator 12 in response to a foot switch 44, for example, to produce anacoustic standing wave in the acoustic assembly 24. The electricalsignal causes disturbances in the piezoelectric elements 32 in the formof repeated small displacements resulting in large compression forceswithin the material. The repeated small displacements cause thepiezoelectric elements 32 to expand and contract in a continuous manneralong the axis of the voltage gradient, producing longitudinal waves ofultrasonic energy.

In various embodiments, the ultrasonic energy produced by transducer 14can be transmitted through the acoustic assembly 24 to the end effector50 via an ultrasonic transmission waveguide 46. In order for theacoustic assembly 24 to deliver energy to the end effector 50, thecomponents of the acoustic assembly 24 are acoustically coupled to theend effector 50. For example, the distal end of the ultrasonictransducer 14 may be acoustically coupled at the surface 30 to theproximal end of the ultrasonic transmission waveguide 46 by a threadedconnection such as a stud 48.

The components of the acoustic assembly 24 can be acoustically tunedsuch that the length of any assembly is an integral number of one-halfwavelengths (nλ/2), where the wavelength λ is the wavelength of apre-selected or operating longitudinal vibration drive frequency f_(d)of the acoustic assembly 24, and where n is any positive integer. It isalso contemplated that the acoustic assembly 24 may incorporate anysuitable arrangement of acoustic elements.

The ultrasonic end effector 50 may have a length substantially equal toan integral multiple of one-half system wavelengths (λ/2). A distal end52 of the ultrasonic end effector 50 may be disposed at, or at leastnear, an antinode in order to provide the maximum, or at least nearlymaximum, longitudinal excursion of the distal end. When the transducerassembly is energized, in various embodiments, the distal end 52 of theultrasonic end effector 50 may be configured to move in the range of,for example, approximately 10 to 500 microns peak-to-peak and preferablyin the range of approximately 30 to 150 microns at a predeterminedvibrational frequency.

As outlined above, the ultrasonic end effector 50 may be coupled to theultrasonic transmission waveguide 46. In various embodiments, theultrasonic end effector 50 and the ultrasonic transmission guide 46 asillustrated are formed as a single unit construction from a materialsuitable for transmission of ultrasonic energy such as, for example,Ti6Al4V (an alloy of titanium including aluminum and vanadium),aluminum, stainless steel, and/or any other suitable material.Alternately, the ultrasonic end effector 50 may be separable (and ofdiffering composition) from the ultrasonic transmission waveguide 46,and coupled by, for example, a stud, weld, glue, quick connect, or othersuitable known methods. The ultrasonic transmission waveguide 46 mayhave a length substantially equal to an integral number of one-halfsystem wavelengths (λ/2), for example. The ultrasonic transmissionwaveguide 46 may be preferably fabricated from a solid core shaftconstructed out of material that propagates ultrasonic energyefficiently, such as titanium alloy (i.e., Ti6Al4V) or an aluminumalloy, for example.

In various embodiments, referring to FIG. 2, the ultrasonic transmissionwaveguide 46 can comprise a longitudinally projecting attachment post 54at a proximal end to couple to the surface 30 of the acoustic assemblyby a threaded connection such as the stud 48. The distal end of theultrasonic transmission waveguide 46 may be coupled to the proximal endof the end effector 50 by an internal threaded connection, for example,preferably at or near an antinode. It is contemplated that the endeffector 50 may be attached to the ultrasonic transmission waveguide 46by any suitable means, such as a welded joint or the like, for example.Although the end effector 50 may be detachable from the ultrasonictransmission waveguide 46, it is also contemplated that the end effector50 and the ultrasonic transmission waveguide 46 may be formed as asingle unitary piece.

In various embodiments, further to the above, FIG. 2 illustrates oneembodiment of a connection union/joint 70 for an ultrasonic instrument.The connection union/joint 70 may be formed between the attachment post54 of the ultrasonic transmission waveguide 46 and the surface 30 of thevelocity transformer 28 at the distal end of the acoustic assembly 24.The proximal end of the attachment post 54 comprises a female threadedsubstantially cylindrical recess 66 to receive a portion of the threadedstud 48 therein. The distal end of the velocity transformer 28 also maycomprise a female threaded substantially cylindrical recess 68 toreceive a portion of the threaded stud 48. The recesses 66, 68 aresubstantially circumferentially and longitudinally aligned.

In the embodiment illustrated in FIG. 1, the ultrasonic transmissionwaveguide 46 comprises a plurality of stabilizing silicone rings orcompliant supports 56 positioned at, or at least near, a plurality ofnodes. The silicone rings 56 can dampen undesirable vibration andisolate the ultrasonic energy from a sheath 58 at least partiallysurrounding waveguide 46, thereby assuring the flow of ultrasonic energyin a longitudinal direction to the distal end 52 of the end effector 50with maximum efficiency.

As shown in FIG. 1, the sheath 58 can be coupled to the distal end ofthe handpiece assembly 60. The sheath 58 generally includes an adapteror nose cone 62 and an elongated tubular member 64. The tubular member64 is attached to and/or extends from the adapter 62 and has an openingextending longitudinally therethrough. In various embodiments, thesheath 58 may be threaded or snapped onto the distal end of the housing16. In at least one embodiment, the ultrasonic transmission waveguide 46extends through the opening of the tubular member 64 and the siliconerings 56 can contact the sidewalls of the opening and isolate theultrasonic transmission waveguide 46 therein. In various embodiments,the adapter 62 of the sheath 58 is preferably constructed from Ultem®,for example, and the tubular member 64 is fabricated from stainlesssteel, for example. In at least one embodiment, the ultrasonictransmission waveguide 46 may have polymeric material, for example,surrounding it in order to isolate it from outside contact.

In various embodiments, as described above, a surgical instrument cancomprise a transducer configured to produce longitudinal vibrations, anend effector and/or wave guide operably coupled to the transducer, andother various acoustic assembly components which operably connect,and/or support, the transducer, wave guide, and/or end effector. Incertain embodiments, as also described above, the transducer can producevibrations which can be transmitted to the end effector, wherein thevibrations can drive the transducer, the wave guide, the end effector,and/or the other various components of the acoustic assembly at, ornear, a resonant frequency. In resonance, a longitudinal strain pattern,or longitudinal stress pattern, can develop within the transducer, thewave guide, and/or the end effector, for example. In variousembodiments, referring now to FIGS. 3 and 4, such a longitudinal strainpattern, or longitudinal stress pattern, can cause the longitudinalstrain, or longitudinal stress, to vary along the length of thetransducer, wave guide, and/or end effector, in a sinusoidal, or atleast substantially sinusoidal, manner. In at least one embodiment, forexample, the longitudinal strain pattern can have maximum peaks and zeropoints, wherein the strain values can vary in a non-linear mannerbetween such peaks and zero points.

In various circumstances, further to the above, the longitudinal strain,or longitudinal stress, at any given location within wave guide 146and/or end effector 150, for example, can be pulsed between variousstrain, or stress, states. Referring to FIGS. 3 and 4, for example, thelongitudinal strain within wave guide 146 at Point A can be cycledbetween a tensile, or positive, ∈_(max) and a compressive, or negative,∈_(max), when a cyclical voltage is supplied to the piezoelectricelements 132 of transducer 114, for example, and especially when thesystem substantially comprising wave guide 146, end effector 150, andtransducer 114 is vibrated at or near its resonant frequency. In variouscircumstances, the absolute values of the compressive and tensilemaximum longitudinal strains can be equal, or at least substantiallyequal. Correspondingly, the longitudinal stress within wave guide 146 atPoint A can be can be cycled between a tensile, or positive, σ_(max) anda compressive, or negative, σ_(max) wherein the absolute values of thecompressive and tensile maximum longitudinal stresses can be equal, orat least substantially equal. Similarly, referring to FIG. 4, thelongitudinal strain within transducer 114 at Point B can be cycledbetween a tensile ∈_(max) and a compressive ∈_(max) and the longitudinalstress can by cycled between a tensile σ_(max) and a compressiveσ_(max).

In various embodiments, as outlined above, the longitudinal strain, orlongitudinal stress, within any given point within wave guide 146 and/orend effector 150 can be cycled between two values, the absolute valuesof which can be substantially the same. In such embodiments, the rangeof longitudinal strain, or longitudinal stress, incurred at a locationcan be evaluated as a peak-to-peak value, i.e., ∈_(ptp) or σ_(ptp),respectively. In at least one embodiment, although not illustrated, thevoltage supplied to piezoelectric elements 132 of transducer 114 can berectified such that the voltage is cycled between zero and a maximumvoltage or, alternatively, between zero and a minimum voltage wherein,as a result, the longitudinal strain profile can be cycled between zeroand a maximum compressive strain or, alternatively, between zero and amaximum tensile strain. In any event, referring again to thelongitudinal stress and longitudinal strain patterns depicted in FIG. 3,the stress pattern is illustrated as overlapping the strain pattern. Invarious circumstances, however, the longitudinal stress and longitudinalstrain within any given point in wave guide 146 and/or end effector 150will not have the same magnitude. Rather, the magnitude of the stress,measured in psi, for example, may be larger, and most likelysubstantially larger, than the magnitude of the strain, measured in anin/in unitless dimension. In various circumstances, the stress (σ) andstrain (∈) values can be linearly proportional and can be related by therelationship:

σ=E*∈

wherein E comprises the modulus of elasticity of the material of thewave guide 146 and/or end effector 150, for example, at a particularpoint.

In various embodiments, a longitudinal strain pattern, or longitudinalstress pattern, within transducer 116, wave guide 146 and/or endeffector 150, as depicted in FIGS. 3 and 4, for example, can compriseone or more zero-strain, or one or more zero-stress, points. Inconjunction with FIGS. 5 and 6, the zero-strain and zero-stress pointswithin transducer 116, wave guide 146, and end effector 150 can coincidewith the anti-nodes of the standing wave of vibrations within transducer116, wave guide 146, and end effector 150, wherein the anti-nodes arerepresented by Points AN. As the reader will recall, referring to FIGS.5 and 6, the anti-nodes of a standing wave of longitudinal vibrationscan correspond with the maximum longitudinal vibrational displacement,i.e., δ_(max) and/or −δ_(max), for example, of the standing wave ofvibrations. Furthermore, the maximum-strain and maximum-stress pointswithin transducer 116, wave guide 146, and end effector 150 can coincidewith the nodes of the standing wave of vibrations which are representedby points N. As the reader will also recall, referring to FIGS. 5 and 6,the nodes of a standing wave of longitudinal vibrations can correspondwith the zero longitudinal displacement points of the standing wave ofvibrations. As illustrated in FIG. 3, referring to the discussion above,Point A is at or near a node N. As also illustrated in FIG. 3, thedistal end 152 of end effector 150 is positioned at or near an antinodeAN and, similarly, the proximal end of wave guide 146 is also positionedat an antinode AN. As discussed above, certain advantages can beobtained by assuring that the distal end 152 of end effector 150 ispositioned at, or near, an antinode, wherein at least one such advantagecan include capitalizing on the maximum longitudinal vibrationdisplacement realized at an antinode, for example. Certain otheradvantages can be obtained by assuring that the proximal end of waveguide 146 is positioned at, or near, an antinode, wherein at least onesuch advantage can include capitalizing on the longitudinal zero strain,or longitudinal zero stress, point realized at an antinode. Similar tothe above, the proximal end of wave guide 146 can comprise a connectionor union joint, such as the connection joint 70 illustrated in FIG. 2,for example, and, by placing this connection joint at or near anantinode, the joint may be exposed to little, if any, longitudinalstress or longitudinal strain induced by the standing wave ofvibrations.

As described above, a voltage, or power, source can be operably coupledwith one or more of the piezoelectric elements of a transducer, whereina voltage potential applied to each of the piezoelectric elements cancause the piezoelectric elements to expand and contract, or vibrate, ina longitudinal direction. As also described above, the voltage potentialcan be cyclical and, in various embodiments, the voltage potential canbe cycled at a frequency which is the same as, or nearly the same as,the resonant frequency of the system of components comprising transducer116, wave guide 146, and end effector 150, for example. In variousembodiments, however, certain of the piezoelectric elements within thetransducer may contribute more to the standing wave of longitudinalvibrations than other piezoelectric elements within the transducer. Moreparticularly, a longitudinal strain profile may develop within atransducer wherein the strain profile may control, or limit, thelongitudinal displacements that some of the piezoelectric elements cancontribute to the standing wave of vibrations, especially when thesystem is being vibrated at or near its resonant frequency.

Referring now to FIG. 7, piezoelectric elements 232 a, which arepositioned closer to node N than the other piezoelectric elements oftransducer 214, can be subjected to a larger strain, or stress, than theother piezoelectric elements of transducer 214. In various embodiments,the strain within a piezoelectric element can determine the amount ofcurrent that can flow, or be drawn through, the piezoelectric element.In certain embodiments, the strain and the current can be linearlyproportional while, in other embodiments, the strain and the current canbe geometrically proportional. As piezoelectric elements 232 a arepositioned closest to the node within transducer 214, and thus exposedto the highest strain, piezoelectric elements 232 a may be able to drawmore current from the power source than the other piezoelectric elementswhich are positioned further away from the node and exposed to lesserstrains. The larger currents flowing through piezoelectric elements 232a, for example, can cause piezoelectric elements 232 a to have largerlongitudinal vibrations and contribute larger displacements to thestanding wave of vibrations within transducer 214, and an end effectorattached thereto, than the other piezoelectric elements of transducer214 which are positioned further away from the node. In certainembodiments, the current drawn by a piezoelectric element and thelongitudinal displacement of the piezoelectric element can be linearlyproportional while, in other embodiments, the current and thelongitudinal displacement can be geometrically proportional.

By way of example, further to the above, piezoelectric elements 232 aare closer to node N than piezoelectric elements 232 b and, asillustrated in FIG. 7, piezoelectric elements 232 b may be subjected toless strain than piezoelectric elements 232 a. As a result, inaccordance with the above, piezoelectric elements 232 b may draw lesscurrent than piezoelectric elements 232 a. Furthermore, as the powerconsumed by a piezoelectric element can be defined by the product of thecurrent flowing through the piezoelectric element and the voltagepotential applied across the piezoelectric element, piezoelectricelements 232 b may consume less power than piezoelectric elements 232 a.Such a relationship may be especially true in embodiments in which thevoltage potential across piezoelectric elements 232 a and 232 b is thesame, or at least substantially the same. Correspondingly, piezoelectricelements 232 c may draw less current and consume less power thanpiezoelectric elements 232 b and, similarly, piezoelectric elements 232d may draw less current and consume less power than piezoelectricelements 232 c.

Further to the above, piezoelectric elements which draw larger currentsand consume larger quantities of power can perform larger quantities ofwork. More particularly, such piezoelectric elements can create largerlongitudinal displacements and/or generate larger longitudinal forceswhen they are vibrated and, as the work produced by a piezoelectricelement can be proportional to the product of the forces and thedisplacements that are generated by the piezoelectric element, suchpiezoelectric elements can output more work. As a result of the above,piezoelectric elements which are positioned closer to a node may producemore work than piezoelectric elements which are positioned further awayfrom the node. This may be especially true in embodiments where thepiezoelectric elements of a transducer are comprised of the samematerial and are substantially the same size. In various embodiments,however, piezoelectric elements which consume larger quantities of powerand perform larger quantities of work can generate larger quantities ofheat. In at least one embodiment, as a result, the piezoelectricelements positioned closest to the node may produce more heat thanpiezoelectric elements which are positioned further away from the node.In various circumstances, the flow of heat away from the piezoelectricelements positioned closest to the node may be inhibited as suchpiezoelectric elements may be positioned intermediate adjacentpiezoelectric elements which may reduce the flow of air therearound. Incertain circumstances, larger quantities of heat can have a negativeimpact on the performance of various piezoelectric elements. Forexample, larger quantities of heat can produce pyroectricity within oneor more of the piezoelectric elements which can counteract the voltagepotential applied thereto and/or possibly reduce the life of thepiezoelectric elements.

In various embodiments, further to the above, a transducer can compriseseveral different piezoelectric elements, wherein the piezoelectricelements can be selected in order to equalize, or at least betterdistribute, the work performed by the piezoelectric elements of thetransducer. In certain embodiments, piezoelectric elements positionedfurther away from a node may produce the same work as piezoelectricelements positioned closer to the node. In certain other embodiments,piezoelectric elements positioned further away from a node may notproduce the same work as piezoelectric elements positioned closer to thenode, but they may produce approximately 90%, approximately 80%,approximately 70%, approximately 60%, approximately 50%, approximately40%, and/or approximately 30% of the work produced by piezoelectricelements positioned closer to the node. In at least one embodiment, thedifferent piezoelectric elements can be comprised of materials whichhave different strain constants (d₃₃), wherein the strain constant of amaterial can be expressed as the ratio of the strain (∈) produced withina material divided by the electric field (E) experienced by thepiezoelectric element. In at least one such embodiment, referring againto FIG. 7, for example, piezoelectric elements 232 a can be comprised ofa first material having a first strain constant and piezoelectricelements 232 b can be comprised of a second material having a secondstrain constant, for example. In various embodiments, the first strainconstant can be higher than the second strain constant. Generally, thecurrent needed by a piezoelectric element to produce a certain amount ofwork can be inversely proportional to the strain constant of thepiezoelectric element and, thus, selecting a material for apiezoelectric element which has a higher strain constant can reduce thecurrent that the piezoelectric element will draw and, correspondingly,reduce the heat that the piezoelectric element will produce.Correspondingly, selecting a material for a piezoelectric element whichhas a lower strain constant can increase the current required to producea certain amount of work, and thus increase the heat that thepiezoelectric element will produce.

Further to the above, the work produced by the piezoelectric elements ofa transducer can be balanced, or at least more evenly balanced, byutilizing piezoelectric elements comprised of a material having a higherstrain constant closer to a node and utilizing piezoelectric elementscomprised of a material having a lower strain constant further away fromthe node. In various embodiments, piezoelectric elements 232 a can becomprised of a first material having a first strain constant,piezoelectric elements 232 b can be comprised of a second materialhaving a second strain constant, piezoelectric elements 232 c can becomprised of a third material having a third strain constant, andpiezoelectric elements 232 d can be comprised of a fourth materialhaving a fourth strain constant, wherein, in at least one embodiment,the first strain constant can be larger than the second strain constant,the second strain constant can be larger than the third strain constant,and the third strain constant can be larger than the fourth strainconstant. In various embodiments, the strain constants of thepiezoelectric elements can range between approximately 100 e⁻12 m/V andapproximately 600 e⁻12 m/V, and/or between approximately 150e⁻12 m/V andapproximately 500 e⁻12 m/V, and/or between approximately 150 e⁻12 m/Vand approximately 350 e⁻12 m/V, for example. In any event, owing to theselection of materials for the piezoelectric elements, referring againto FIG. 7, piezoelectric elements 232 b may produce the same quantity ofwork as, or at least a large fraction of, the work produced bypiezoelectric elements 232 a, for example, and, similarly, piezoelectricelements 232 c may produce the same quantity of work as, or at least alarge fraction of, the work produced by piezoelectric elements 232 b,for example. Likewise, piezoelectric elements 232 d may produce the samequantity of work as, or at least a large fraction of, the work producedby piezoelectric elements 232 c.

In various embodiments, as a result of the above, the heat generated bythe piezoelectric elements of a transducer can be balanced, or at leastmore evenly balanced, such that the heat is generated evenly, or atleast more evenly, throughout the transducer. Such embodiments canprevent, or at least reduce the possibility of, an undesirable quantityof heat from being generated and/or retained within a single, orcentralized, location within the transducer, for example. In certaincircumstances, as a result of the above, piezoelectric elements 232 bmay generate the same quantity of heat as, or at least a large fractionof, the heat generated by piezoelectric elements 232 a, for example,and, similarly, piezoelectric elements 232 c may generate the samequantity of heat as, or at least a large fraction of, the heat generatedby piezoelectric elements 232 b, for example. Likewise, piezoelectricelements 232 d may generate the same quantity of heat as, or at least alarge fraction of, the heat generated by piezoelectric elements 232 c.In at least one such embodiment, the heat generated and/or retained bythe piezoelectric elements can be evenly distributed, or at least moreevenly distributed, within the transducer 214. In various embodiments,the additional heat generated and/or retained within piezoelectricelements 232 d, for example, can be more easily drawn into distal endmember 222 and/or proximal end member 220, for example, such that theheat can be more easily dissipated from transducer 214. In certainembodiments, end members 220 and 222 can comprise heat sinks which candraw heat away from the piezoelectric elements, wherein, in at least oneembodiment, end members 220 and 222 can be comprised of metal, forexample. In such embodiments, the possibility of the piezoelectricelements becoming overheated can be reduced.

In various alternative embodiments, it may be desirable to utilizepiezoelectric elements comprised of a material having a lower strainconstant closer to a node and piezoelectric elements comprised of amaterial having a higher strain constant further away from the node. Invarious embodiments, piezoelectric elements 232 a can be comprised of afirst material having a first strain constant, piezoelectric elements232 b can be comprised of a second material having a second strainconstant, piezoelectric elements 232 c can be comprised of a thirdmaterial having a third strain constant, and piezoelectric elements 232d can be comprised of a fourth material having a fourth strain constant,wherein, in at least one embodiment, the first strain constant can besmaller than the second strain constant, the second strain constant canbe smaller than the third strain constant, and the third strain constantcan be smaller than the fourth strain constant.

In certain embodiments, further to the above, the heat generated by thepiezoelectric elements of a transducer can be balanced, or at least moreevenly balanced, by utilizing materials having different dielectricdissipation or dampening properties. In various circumstances, thedielectric dissipation of a material can be expressed as the measure ofthe loss-rate of power of a mode of oscillation in a dissipative system.Stated another way, in certain circumstances, the dielectric dissipationof a material can represent the energy dissipation, or losses, that canoccur within a vibrating piezoelectric element, and/or transducer,wherein such dissipation, or losses, can result in heat generation. Inany event, in various embodiments, different materials can be utilizedwhich have larger and/or smaller dissipative or dampening qualities,wherein materials having smaller dissipative or dampening qualities maygenerate less heat, for example. In at least one embodiment,piezoelectric elements comprised of materials having smaller dissipativequalities can be positioned closer to a node whereas piezoelectricelements comprised of materials having larger dissipative qualities canbe positioned further away from a node. In various embodiments, thedielectric dissipation factor of the piezoelectric materials of atransducer can range between approximately 0.002 and approximately 0.01,for example.

In certain embodiments, further to the above, the work generated by thepiezoelectric elements of a transducer can be balanced, or at least moreevenly balanced, by utilizing materials having different dielectricconstants. In various embodiments, piezoelectric elements comprised ofmaterials having a lower dielectric constant may be able to produce morework than piezoelectric elements having a higher dielectric constant. Inat least one embodiment, as a result, piezoelectric elements 232 a canbe comprised of a first material having a first dielectric constant,piezoelectric elements 232 b can be comprised of a second materialhaving a second dielectric constant, piezoelectric elements 232 c can becomprised of a third material having a third dielectric constant, andpiezoelectric elements 232 d can be comprised of a fourth materialhaving a fourth dielectric constant, wherein, in at least oneembodiment, the first dielectric constant can be larger than the seconddielectric constant, the second dielectric constant can be larger thanthe third dielectric constant, and the third dielectric constant can belarger than the fourth dielectric constant. In various embodiments,further to the above, the relative dielectric constants of thepiezoelectric materials can range between approximately 900 andapproximately 1200, for example, wherein the relative dielectricconstant of a material (∈_(r)) can be defined as the static permittivityof the material (∈_(s)) divided by the permittivity constant (∈_(o)). Inany event, owing to the selection of materials for the piezoelectricelements, referring again to FIG. 7, piezoelectric elements 232 b mayproduce the same quantity of work as, or at least a large fraction of,the work produced by piezoelectric elements 232 a, for example, and,similarly, piezoelectric elements 232 c may produce the same quantity ofwork as, or at least a large fraction of, the work produced bypiezoelectric elements 232 b, for example. Likewise, piezoelectricelements 232 d may produce the same quantity of work as, or at least alarge fraction of, the work produced by piezoelectric elements 232 c.

In certain embodiments, further to the above, the work generated by thepiezoelectric elements of a transducer can be balanced, or at least moreevenly balanced, by utilizing materials having different voltagesensitivities. In various embodiments, piezoelectric elements comprisedof materials having a higher voltage sensitivity may be able to producemore work than piezoelectric elements having a lower voltagesensitivity. In at least one embodiment, as a result, piezoelectricelements 232 a can be comprised of a first material having a firstvoltage sensitivity, piezoelectric elements 232 b can be comprised of asecond material having a second voltage sensitivity, piezoelectricelements 232 c can be comprised of a third material having a thirdvoltage sensitivity, and piezoelectric elements 232 d can be comprisedof a fourth material having a fourth voltage sensitivity, wherein, in atleast one embodiment, the first voltage sensitivity can be smaller thanthe second voltage sensitivity, the second voltage sensitivity can besmaller than the third voltage sensitivity, and the third voltagesensitivity can be smaller than the fourth voltage sensitivity. Invarious embodiments, the voltage sensitivity of a piezoelectric materialcan be defined as the responsiveness, or change in shape, of thematerial to a voltage potential, wherein piezoelectric materials havinga higher voltage sensitivity may require less voltage to produce largerdisplacements within the material. In any event, owing to the selectionof materials for the piezoelectric elements, referring again to FIG. 7,piezoelectric elements 232 b may produce the same quantity of work as,or at least a large fraction of, the work produced by piezoelectricelements 232 a, for example, and, similarly, piezoelectric elements 232c may produce the same quantity of work as, or at least a large fractionof, the work produced by piezoelectric elements 232 b, for example.Likewise, piezoelectric elements 232 d may produce the same quantity ofwork as, or at least a large fraction of, the work produced bypiezoelectric elements 232 c.

As discussed above, referring again to FIG. 7, the piezoelectricelements of a transducer which are positioned closer to a node maygenerate and/or retain more heat than the piezoelectric elements of atransducer which are positioned further away from a node. As alsodiscussed above, the materials of the piezoelectric elements can beselected such that the heat produced and/or retained by thepiezoelectric elements can be leveled, or at least better leveled,across the transducer. In various circumstances, however, heatgeneration and/or retention may be centralized within the piezoelectricelements near the node. In various embodiments, as discussed in greaterdetail below, the piezoelectric elements of a transducer can becomprised of different materials having different Currie temperatures(T_(c)). The Curie temperature of piezoelectric materials can bedescribed as the temperature above which a piezoelectric material maylose its polarization and piezoelectric characteristics. In variouscircumstances, as a result, it may be desirable that the temperatures ofthe piezoelectric materials do not exceed their Currie temperatures.

In various embodiments, especially in embodiments where there is a largethermal gradient in the transducer between the piezoelectric elements232 a at the center, or node, of the transducer stack and thepiezoelectric elements 232 d at the ends, or antinodes, of thetransducer stack, the piezoelectric elements positioned closer to thenode can be comprised of a material having a higher Currie temperaturethan the Curie temperature of the piezoelectric elements positionedfurther away from the node. In at least one embodiment, piezoelectricelements 232 a can be comprised of a first material having a firstCurrie temperature, piezoelectric elements 232 b can be comprised of asecond material having a second Currie temperature, piezoelectricelements 232 c can be comprised of a third material having a thirdCurrie temperature, and piezoelectric elements 232 d can be comprised ofa fourth material having a fourth Currie temperature, wherein, in atleast one embodiment, the first Currie temperature can be larger thanthe second Currie temperature, the second Currie temperature can belarger than the third Currie temperature, and the third Currietemperature can be larger than the fourth Currie temperature. In atleast one such embodiment, for example, piezoelectric elements 232 aand/or 232 b, for example, can be comprised of (K,Na) NbO₃, which iscommonly-referred to as sodium potassium niobate or “KNN” and has aCurrie temperature of approximately 410° C. Further to the above,piezoelectric elements 232 a and/or 232 b can be comprised of Bi4Ti3O12,which is commonly-referred to as “BTO” and has a Currie temperature ofapproximately 280° C., and/or (Bi,Na)TiO₃—(Bi,K)TiO₃—(Ba,Sr)TiO₃, whichis commonly-referred to as “BNBK” and has a Currie temperature ofapproximately 675° C., and/or any suitable high Tc lead-freepiezoelectric material, for example. In addition to the above,piezoelectric elements 232 c and/or 232 d, for example, can be comprisedof BaTiO3, which is commonly-referred to as barium titanate and has aCurrie temperature of approximately 110° C., and/or any suitable low Tclead-free piezoelectric material, for example. In at least oneembodiment, piezoelectric elements 232 a can be comprised of BNBK(T_(c)=675° C.), piezoelectric elements 232 b can be comprised of KNN(T_(c)=410° C.), piezoelectric elements 232 c can be comprised of BTO(T_(c)=280° C.), and piezoelectric elements 232 d may be comprised ofbarium titanate (T_(c)=110° C.), for example. Although such arrangementsmay be useful in various circumstances, each of the piezoelectricelements within a transducer stack can be comprised of one or more ofany of the materials mentioned herein.

In various embodiments, further to the above, the first piezoelectricelements 232 a having a first Currie temperature can draw a firstcurrent, the second piezoelectric elements 232 b having a second Currietemperature can draw a second current, wherein the first current can belarger in magnitude than the second current. Owing to a higher firstCurrie temperature, the first, or higher, current may not detrimentallyoverheat the first piezoelectric elements 232 a and, similarly, thesecond, or lower, current may not detrimentally overheat the secondpiezoelectric elements 232 b. In at least one such embodiment, the thirdpiezoelectric elements 232 c can draw a third current which has a lowermagnitude than the second current and, in addition, the fourthpiezoelectric elements 232 d can draw a fourth current which has a lowermagnitude than the third current.

In various embodiments, referring now to FIGS. 8-13, piezoelectricelements having different thicknesses can be utilized to distribute thework produced by, and the current drawn by, the piezoelectric elementsof a transducer. Referring to FIG. 8, transducer 314 a, for example, cancomprise four piezoelectric elements 332 having a first thickness andfour piezoelectric elements 333 having a second thickness, for example,wherein the second thickness is larger than the first thickness. In suchembodiments, piezoelectric elements 332 and 333 can be arranged suchthat the work produced the piezoelectric elements can generate a workprofile as illustrated in FIG. 14. Referring to FIGS. 8 and 14, thethicker piezoelectric elements 333 are positioned closer to node N thanthe thinner piezoelectric elements 332 wherein, owing to the arrangementof piezoelectric elements 332 and 333 and the longitudinal stressprofile ∈(l) generated within the transducer, the work produced by thepiezoelectric elements may not be distributed evenly across thepiezoelectric elements. In fact, referring to FIG. 14, the work producedby the transducer may be heavily concentrated in the large piezoelectricelements 333 positioned proximate to the node N. Correspondingly, thethinner piezoelectric elements 332 of transducer 314 may produce farless work than piezoelectric elements 333 as they are positioned furtheraway from node N and closer to antinodes AN and, as a result, aresubjected to less longitudinal strain.

In various embodiments, referring now to transducers 314 b, 314 c, 314e, and 314 f illustrated in FIGS. 9, 10, 12, and 13, respectively,piezoelectric elements 332 and 333 can be stacked in differentarrangements, wherein the different arrangements can produce differentwork profiles. In various embodiments, further to the above, thepiezoelectric elements of a transducer can be arranged such that thework profile produced by the piezoelectric elements is level across thetransducer, or at least more closely approximating a level work profilethan the work profile produced by transducer 314 a, for example. In atleast one embodiment, referring now to FIG. 11, transducer 314 d,similar to the above, can comprise four piezoelectric elements 332 andfour piezoelectric elements 333, for example. In such embodiments,piezoelectric elements 332 and 333 of transducer 314 d can be arrangedsuch that the work produced the piezoelectric elements may generate awork profile as illustrated in FIG. 14. More particularly, referring toFIGS. 11 and 14, the thinner piezoelectric elements 332 of transducer314 d are positioned closer to node N than the thicker piezoelectricelements 333 wherein, owing to the arrangement of piezoelectric elements332 and 333, the work produced by the piezoelectric elements oftransducer 314 d may be more evenly distributed across the piezoelectricelements. By way of comparison, the large concentration, or peak, ofwork centralized around node N that may be produced by transducer 314 amay be noticeably larger than the less-pronounced concentration of workcentralized around node N that may be produced by transducer 314 d.Furthermore, by way of comparison, the thicker piezoelectric elements333 positioned at the ends of the transducer stack of transducer 314 dmay produce more work than the thinner piezoelectric elements 332positioned at the ends of the transducer stack of transducer 314 a,thereby further leveling the work profile of transducer 314 d.

While it is possible that the work profiles illustrated in FIG. 14 mayrepresent the actual work profiles of various transducers, such workprofiles have been provided for the purposes of demonstration anddiscussion. Various other work profiles may be possible. Referring toFIG. 14, the reader will note that the horizontal axis is marked withthe numbers 1-8 which represent the eight piezoelectric elements of theexemplary embodiments of transducers 314 a and 314 d, for example. Moreparticularly, the number 1 may represent the first, or most proximal,piezoelectric element, the number 2 may represent the second, orsecond-most proximal, piezoelectric element, and so forth. The readerwill also note that the vertical axis is marked with percentage values.Such percentage values represent the current that a particularpiezoelectric element may draw as compared to the total current drawn bythe transducer. For example, the first piezoelectric element oftransducer 314 a may draw approximately 10.5% of the total current drawnby transducer 314 a while the first piezoelectric element of transducer314 d may draw approximately 11.5% of the total current drawn bytransducer 314 d. In various embodiments, in view of the above, if thepercentages of current drawn by each piezoelectric element of transducer314 a were summed, the result should total 100%. Similarly, thepercentages of the current drawn by each piezoelectric element oftransducer 314 d, when summed, should also total 100%.

In various embodiments, as outlined above, the longitudinal strainprofile produced by the standing wave of vibrations within a transducercan be sinusoidal, wherein the longitudinal strain can vary in anon-linear or geometric manner between first and second values. Incertain embodiments, referring once again to FIG. 8, the strain profile∈(l) within transducer 314 a can be represented by a half-sine waveextending between two antinodes AN of the standing wave of vibrations,for example, although other embodiments are envisioned in which anysuitable number of antinodes can be located within a transducer.Alternatively, embodiments are envisioned in which no antinodes arelocated within a transducer. In any event, as also outlined above, themaximum longitudinal strain of the strain profile ∈(l) can occur at thenode N of the standing wave of vibrations, wherein the piezoelectricelements positioned closest to node N, such as piezoelectric elements333 ₃ and 333 ₄ of transducer 314 a, for example, can be subjected tothe most longitudinal strain. For example, referring to FIG. 8,piezoelectric elements 333 ₃ and 333 ₄ are positioned just to the leftof, or proximal with respect to, node N, wherein the element 333 ₄ issubjected to a longitudinal strain ∈₄ and the element 333 ₃ is subjectedto a longitudinal strain ∈₃, wherein strain ∈₄ is less than ∈_(max), andwherein strain ∈₃ is less than strain ∈₄. For the purposes of thisexample, longitudinal strain ∈₄ can represent the average strain acrosspiezoelectric element 333 ₄ and longitudinal strain ∈₃ can represent theaverage strain across piezoelectric element 333 ₃. Correspondingly,referring again to FIG. 8, longitudinal strain ∈₃ and longitudinalstrain ∈₄ are illustrated as occurring in the center of thepiezoelectric elements 333 ₃ and 333 ₄, respectively. In any event,further to the above, strain ∈₃ and strain ∈₄ may allow piezoelectricelements 333 ₃ and 333 ₄ to contribute larger quantities of work thanthe piezoelectric elements 332 ₂ and 332 ₁ positioned proximally withrespect to piezoelectric elements 333 ₃ and 333 ₄, wherein piezoelectricelements 332 ₂ and 332 ₁ are subjected to longitudinal strain ∈₂ andlongitudinal strain ∈₁, respectively. Similar to the above, strains ∈₂and ∈₁ can represent the average longitudinal strains experienced acrosspiezoelectric elements 332 ₂ and 332 ₁, for example.

Further to the above, referring again to FIG. 8, longitudinal strain ∈₂is less than longitudinal strain ∈₃ and, in addition, longitudinalstrain ∈₁ is less than strain ∈₂ and significantly less than strain ∈₄.Such a relationship is due to the sinusoidal nature, or shape, of thestrain profile ∈(l). Owing to such a shape, more particularly, thelongitudinal strain induced within the transducer can decrease in ageometric, or non-linear, manner with respect to node N and, as aresult, the strain profile within the transducer can experience largerchanges in longitudinal strain at locations further away from node N,and/or locations closer to an antinode AN. As a result, piezoelectricelements positioned further away from the node N may be subjected tosignificantly less longitudinal strain and may be less capable ofproducing larger quantities of work. In order to better balance the workdistribution of the piezoelectric elements of a transducer, referringonce again to FIG. 11, the piezoelectric elements can be arranged suchthat the differences in average longitudinal strain experienced acrossthe piezoelectric elements can be reduced. In at least one comparativeexample, referring to FIGS. 8 and 11, the piezoelectric elements oftransducer 314 d can be arranged such that the distance Bl1 between thenode N and the center of piezoelectric element 333 ₁ of transducer 314 dis less than the distance Al1 between the node N and the center ofpiezoelectric element 332 ₁ of transducer 314 a. Owing to the fact thatdistance Bl1 is shorter than distance Al1, the average longitudinalstrain experienced within, and the work produced by, piezoelectricelement 333 ₁ of transducer 314 d may be greater than the average strainexperienced within, and the work produced by, piezoelectric element 332₁ of transducer 314 a. Owing to the increase in work that piezoelectricelement 333 ₁ of transducer 314 d can provide, the difference in workproduced by piezoelectric element 333 ₁ and piezoelectric element 332 ₄of transducer 314 d can be less than the difference in work produced bypiezoelectric elements 332 ₁ and piezoelectric element 333 ₄ oftransducer 314 a, for example.

Further to the above, referring again to FIGS. 8 and 11, the distanceBl2 between the node N and the center of piezoelectric element 333 ₂ oftransducer 314 d is less than the distance Al2 between the node N andthe center of piezoelectric element 332 ₂ of transducer 314 a. Owing tothe fact that distance Bl2 is shorter than distance Al2, similar to theabove, the average strain experienced within, and work produced by,piezoelectric element 333 ₂ of transducer 314 d may be greater than theaverage strain experienced within, and the work produced by,piezoelectric element 332 ₂ of transducer 314 a. Owing to the increasein work that piezoelectric element 333 ₂ of transducer 314 d canprovide, similar to the above, the difference in work produced bypiezoelectric element 333 ₂ and piezoelectric element 332 ₄ oftransducer 314 d can be less than the difference in work produced bypiezoelectric elements 332 ₂ and piezoelectric element 333 ₄ oftransducer 314 a, for example. Similarly, distance Bl3 can be shorterthan distance Al3 with regard to the third piezoelectric element and, inaddition, distance Bl4 can be shorter than distance Al4 with regard tothe fourth piezoelectric element, i.e., the element positioned closestto node N. As illustrated in FIGS. 8 and 11, the other piezoelectricelements of transducers 314 a and 314 d, i.e., elements 333 ₅, 333 ₆,332 ₇, and 332 ₈ of transducer 314 a and elements 332 ₅, 332 ₆, 333 ₇,and 333 ₈ of transducer 314 d, can be arranged in a corresponding, ormirror-image, manner, wherein the above-provided discussion is adaptablewith respect to these elements with regard to node N and the second, oropposite, antinode AN. In any event, referring once again to FIG. 14,the work produced by the piezoelectric elements across the transducercan be leveled, or at least more closely leveled, by arranging thepiezoelectric elements such that the average strain that each element issubjected to is the same, or closer to being same.

In various embodiments, further to the above, piezoelectric elementswhich are subjected to larger average longitudinal strains can producelarger amplitudes of longitudinal vibrations, especially in thickerpiezoelectric elements, i.e., piezoelectric elements which are thickerin the longitudinal direction. In various circumstances, thelongitudinal strain of a piezoelectric element can be defined as thechange in thickness (Δt) of the piezoelectric element divided by itsoriginal, or unenergized, thickness (t₀) and, when the longitudinalstrain within the piezoelectric element is dictated by the generatedstrain field within a resonating transducer, the utilization of thickerpiezoelectric elements may demand that larger longitudinal displacementsoccur within the piezoelectric elements in order for the relative ratioof (Δt/t₀) to be maintained. Stated another way, for a givenlongitudinal strain value, a larger (t₀) may dictate a larger Δt and,correspondingly, a smaller (t₀) may dictate a smaller Δt. As outlinedabove, referring again to FIG. 11, the thicker piezoelectric elements333 of transducer 314 d are positioned further away from node N thanpiezoelectric elements 332 and, although the thicker elements 333 may besubjected to a smaller average strains than the thinner elements 332,the thickness of piezoelectric elements 333 may compensate for thesmaller average strains and may still provide sufficient longitudinaldisplacements, or vibrations, and produce sufficient quantities of worksuch that the work profile produced by transducer 314 d is level, or atleast closer to being level. Although not illustrated, variouspiezoelectric elements can be used within a transducer wherein thepiezoelectric elements can have a variety of different thicknesses, andwherein, in certain embodiments, a transducer can comprise piezoelectricelements having three or more different thicknesses. In certainembodiments, also not illustrated, a transducer can comprisepiezoelectric elements wherein the thickest piezoelectric elements arepositioned on the ends of the transducer stack, the thinnestpiezoelectric elements are positioned in the middle of the stack, andpiezoelectric elements having an intermediate thickness are positionedtherebetween such that the thicknesses of these piezoelectric elementsare arranged in a descending order towards the middle of the stack, forexample.

Further to the above, referring again to FIGS. 8-13, the piezoelectricelements of a transducer can have the same, or at least substantiallythe same, width, height, and/or diameter. In certain other embodiments,referring now to FIG. 15, a transducer, such as transducer 414, forexample, can comprise piezoelectric elements having different widths,heights, and/or diameters. More particularly, in at least oneembodiment, transducer 414 can comprise first piezoelectric elements 432a having a first diameter, second piezoelectric elements 432 b having asecond diameter, third piezoelectric elements 432 c having a thirddiameter, and fourth piezoelectric elements 432 d having a fourthdiameter. In such embodiments, the first, second, third, and/or fourthpiezoelectric elements can have different capacitances owing to theirdifferent diameters. More particularly, as discussed above, eachpiezoelectric element can comprise electrodes placed on the oppositesides of the piezoelectric element in order to generate a voltage, orelectric, potential across the element, wherein, owing to the directlyproportional relationship between the surface area of the electrodes andthe potential capacitance of a piezoelectric element, piezoelectricelements having larger diameters can comprise electrodes having largersurface areas and, thus, can generate larger capacitances within thelarger piezoelectric elements. In various circumstances, the directlyproportional relationship between the surface area of the electrodes andthe capacitance of the piezoelectric element can be linear, or at leastsubstantially linear, although embodiments having a geometricrelationship are contemplated. Furthermore, owing to the directlyproportional relationship between the capacitance of a piezoelectricelement and the current flowing through the piezoelectric element, thelarger piezoelectric elements having larger capacitances can draw largercurrents and, thus, perform larger quantities of work. In variouscircumstances, the directly proportional relationship between thecapacitance and the current flowing through the piezoelectric elementcan be linear, or at least substantially linear, although embodimentshaving a geometric relationship are contemplated. In certaincircumstances, the capacitance of a piezoelectric element can berepresented by the relationship provided below:

C=(K*∈ ₀ *A)/t

wherein K represents the dielectric constant of the piezoelectricelement material, wherein ∈₀ represents the permittivity of air, whereinA represents the surface area of the electrodes, and wherein trepresents the thickness of the piezoelectric element between theelectrodes.

Referring once again to FIG. 15, the diameter of piezoelectric elements432 a of transducer 414 can be constant, or at least substantiallyconstant, across the thickness thereof. Similarly, the diameters ofpiezoelectric elements 432 b, 432 c, and/or 432 d can be constant, or atleast substantially constant, across the thicknesses thereof. In atleast one embodiment, such piezoelectric elements can comprise first andsecond electrodes which are positioned on opposite sides thereof whichhave the same, or at least substantially the same, diameter. In variousalternative embodiments, the diameter of one or more piezoelectricelements of a transducer may not be constant across the thicknessthereof. In at least one such embodiment, referring now to FIG. 16,transducer 514 can comprise a piezoelectric element 532 a, for example,which can comprise a first diameter 531 and a second diameter 535,wherein the second diameter 535 can be larger than the first diameter531. As illustrated in FIG. 16, the diameter of piezoelectric element532 a can decrease between the larger second diameter 535 and thesmaller first diameter 531. In various embodiments, the diameter ofpiezoelectric element 532 a can decrease in a linear, or an at leastsubstantially linear, manner, although other changes in diameter arecontemplated, such as non-linear or geometric decreases, for example.

Further to the above, first and second electrodes can be attached to thesides of piezoelectric elements 532 a, wherein the first electrode canhave the same diameter, or at least substantially the same diameter, asfirst diameter 531, and wherein the second electrode can have the samediameter, or at least substantially the same diameter, as seconddiameter 535. Owing to the different diameters and/or areas, A, of thefirst and second electrodes, in various embodiments, the capacitance, C,of piezoelectric element 532 a can be such that the work produced bypiezoelectric element 532 a is consistent with a desired work profile.In certain embodiments, transducer 514 can further comprisepiezoelectric elements 532 b, 532 c, and/or 532 d, wherein the diametersof these piezoelectric elements can also decrease between first andsecond diameters. In at least one embodiment, referring again to FIG.16, the diameters of the piezoelectric elements of transducer 514 candecrease at a constant, or at least substantially constant, rate betweenthe largest diameters of piezoelectric elements 532 d and the smallestdiameters of piezoelectric elements 532 a. In various embodiments,referring now to FIG. 16A, the diameters of the piezoelectric elementsof transducer 2714 can increase at a constant, or at least substantiallyconstant, rate between the smallest diameters of piezoelectric elements2732 d and the largest diameters of piezoelectric elements 2732 a.Although not illustrated, other embodiments are envisioned in which thediameters of the piezoelectric elements increase and/or decrease in anon-linear manner and/or have any other suitable profile. In any event,similar to the above, the larger and smaller diameters of piezoelectricelements 532 a, 532 b, 532 c, and/or 532 d can be arranged such thecapacitances, C, of the piezoelectric elements result in a desired workprofile. More particularly, as outlined above, larger electrodes can beassociated with the larger diameters of the piezoelectric elements ascompared to the smaller electrodes associated with the smallerdiameters, wherein the larger electrodes can be positioned closer to anantinode AN and, as a result, can provide for a more even distributionof work across the work profile. In various other embodiments, referringagain to FIG. 16A, the largest diameters of piezoelectric elements 2732a, 2732 b, 2732 c, and 2732 d can be positioned closer to a node so asto capitalize on larger strain values within the strain profile.

In various embodiments, as outlined above, the piezoelectric elements ofa transducer can generate heat, wherein, in some circumstances,excessive heat may affect the performance of the piezoelectric elements.In certain embodiments, a transducer can comprise a pump. Referring toFIGS. 17 and 18, transducer 614 can comprise one or more straps, orribbons, 617 which can be configured to pump air around one or morepiezoelectric elements 632 of transducer 614 when transducer 614 isactuated as also outlined above. In at least one such embodiment,piezoelectric elements 632 can be positioned intermediate end-bell 620and fore-bell 622, wherein, although not illustrated in FIG. 17,end-bell 620 and fore-bell 622 can be fastened together so as to captureand/or compress piezoelectric elements 632 therebetween. In certaincircumstances, one or more straps 617 can be mounted to end-bell 620 andfore-bell 622 wherein, in at least one embodiment, straps 617 can bemounted to end-bell 620 and fore-bell 622 after end-bell 620 andfore-bell 622 have been bolted together. In at least one embodiment,transducer 614 can comprise four straps 617 which can be welded, and/orotherwise suitably fastened, to end-bell 620 and fore-bell 622, whereinthe straps 617 can be positioned equidistantly, or at leastsubstantially equidistantly, around the perimeter of the transducer.Although straps 617 are illustrated as being rectangular and having aconstant thickness, straps 617 can have any suitable shape and/or anon-constant thickness. In various embodiments, referring to FIG. 17,gaps 637 can be defined between straps 617 and piezoelectric elements632 such that, when straps 617 deflect, as described in greater detailbelow, straps 617 do not contact piezoelectric elements 632.

In various circumstances, referring to FIG. 18, the vibrations producedby piezoelectric elements 632 can cause straps 617 to vibrate anddeflect. The deflections of straps 617 can displace the air surroundingstraps 617, such as the air located intermediate straps 617 andpiezoelectric elements 632, for example, and cause the air to flow overthe piezoelectric elements. In various circumstances, the air flowingover the piezoelectric elements 632 can be, at least initially, coolerthan the piezoelectric elements 632 such that the air can absorb heatfrom the piezoelectric elements 632. In certain embodiments, thetransducer 614 can be positioned within a handle of a surgicalinstrument, wherein the handle can include one or more air vents whichcan allow the warmed air to be exhausted from the handle and allowcooler air to enter the handle and further cool the piezoelectricelements 632. In certain embodiments, a fan having one or more fanblades can be positioned within the handle in order to assist in movingthe cooler air around the piezoelectric elements and/or move the heatedair out of the handle. In various embodiments, referring again to FIG.18, straps 617 can be configured to vibrate or deflect in one or moredirections. In at least one embodiment, straps 617 can be configured todeflect in a direction which is transverse to longitudinal axis 699 suchthat straps 617 pump air in a radial, or at least substantially radial,direction over the piezoelectric elements. In certain embodiments,straps 617 can be configured to deflect in directions which areperpendicular, parallel, and/or skew with respect to longitudinal axis699. In certain embodiments, straps 617 can be configured to produce alaminar flow of air over piezoelectric elements 632, and/or a turbulentflow of air, depending on the geometry and the surface conditions of thepiezoelectric elements. In various embodiments, straps 617 can becomprised of metal, such as copper or brass, for example, wherein straps617 can be configured to conduct heat between end-bell 620 and fore-bell622. In at least one such embodiment, heat can flow from one end oftransducer 614 to the other end such that the heat stored withintransducer 614 can be spread evenly, or at least substantially evenly,throughout transducer 614.

In various embodiments, as outlined above, the piezoelectric elements626 of transducer 614 can generate longitudinal vibrations which cancause straps, or ribbons, 617 to vibrate and deflect. In certaincircumstances, piezoelectric elements 626, for example, can generatevibrations which are transverse or perpendicular to longitudinal axis699, for example, which can cause straps 617 to vibrate and deflect. Insuch circumstances, fairly large deflections of straps 617 can occur. Incertain embodiments, however, straps 617 may not deflect a sufficientamount to produce a desired air flow. In at least one embodiment,referring now to FIG. 19, one or more weights, or masses, 739 can bemounted to one or more straps 717 which can be configured to cause aneccentricity, or imbalance, within straps 717. Owing to such animbalance, the vibrations produced by the piezoelectric elements 732 oftransducer 714 can be amplified, at least initially, to create largerdeflections within straps 717. Stated another way, masses 739 can“kick-off” the deflections of straps 717. In various circumstances, theadditional weight of the masses can cause larger deflections of straps717 throughout the duration in which transducer 714 is operated. In atleast one embodiment, masses 739 can comprise, or at least approximate,point masses which do not stiffen, or at least substantially stiffen,straps 717. In any event, each strap 717 can include one or more massesmounted thereto or, in certain other embodiments, some straps 717 caninclude one or more masses mounted thereto while some straps 717 may nothave any straps mounted thereto at all. In certain embodiments, masses739 can be welded to straps 717 and, in various embodiments, masses 739can be adhered to and/or fastened to straps 717.

In various embodiments, as outlined above, an ultrasonic surgicalinstrument can comprise a cable configured to supply current to thetransducer of the surgical instrument. In certain embodiments, the cablecan be configured to conduct heat away from the transducer and/or ahandpiece of the surgical instrument in which the transducer ispositioned. In at least one embodiment, the cable can comprise severallayers. For example, in at least one such embodiment, a cable cancomprise an inner core, an outer core, a first insulative layerpositioned intermediate the inner core and the outer core, a secondinsulative layer surrounding the outer core, a thermally conductivematerial surrounding the second insulative layer, and an outerinsulative layer. The inner core and the outer core can be configured toconduct current to and from the transducer, wherein the first and secondinsulative layers can be configured to prevent current from leakingtherefrom. The thermally conductive material can be configured to drawheat out of the transducer, and/or handpiece, and conduct the heat outof the surgical instrument. In certain circumstances, the conductivematerial can act as a heat sink and, in at least one embodiment, theconductive material can be comprised of aluminum. In any event, theouter insulative layer can be configured to protect a surgeon, forexample, from touching the hot conductive material during use.

In various embodiments, as discussed above, the vibrations produced by atransducer of an ultrasonic instrument can be transmitted to a waveguide, such as wave guide 46, for example, and an end effector, such asend effector 50, for example. Owing to such vibrations, especially whenthe wave guide and end effector are driven at resonance, the wave guideand end effector may generate and store heat, especially at the nodes ofthe standing wave of vibrations. In some circumstances, such localizedheat generation may be useful. In various circumstances, however, it maybe desirable to distribute the heat generated within the wave guideand/or end effector such that the heat is not localized, or at leastless localized, in one or more locations. In various embodiments,referring to FIGS. 20 and 21, a surgical instrument can comprise a waveguide 846, an end effector 850, and a sheath, such as 841, for example,which can be configured to surround, or at least partially surround, aportion of wave guide 846 and end effector 850. In certain embodiments,a surgical instrument can comprise a pump configured to move air along awave guide and/or end effector. In at least one embodiment, the surgicalinstrument can further include one or more membranes, or diaphragms,extending between sheath 841 and wave guide 846, and/or between sheath841 and end effector 850. In at least one such embodiment, the surgicalinstrument can comprise membranes 843 mounted to sheath 841 and waveguide 846, wherein, when wave guide 846 is subjected to vibrations, asoutlined above, membranes 843 can move, or pump, air along wave guide846 and/or end effector 850. More particularly, in at least oneembodiment, the center portions 845 of membranes 843 can be affixed towave guide 846, for example, such that, when wave guide 846 is subjectedto longitudinal vibrations, the central portions 845 of membranes 843can undergo longitudinal excursions while the outer portions 847 ofmembranes can remain stationary, or at least substantially stationary,as they can be affixed to sheath 841.

Owing to the longitudinal excursions of central portions 845, airpositioned intermediate sheath 841 and wave guide 846, for example, canbe moved longitudinally along wave guide 846 such that the air canabsorb heat generated by and stored within wave guide 846, for example.In certain embodiments, the membranes can produce a laminar and/orturbulent flow of air across the surface of wave guide 846 and endeffector 850. In various embodiments, one or more membranes 843 can bepositioned at the antinodes of the standing wave of vibrations such thatthe larger longitudinal displacements of wave guide 846, which occur atthe antinodes, can be utilized to produce larger displacements ofmembranes 843 and larger flows of air. In at least one such embodiment,a membrane can be positioned at each antinode that occurs within a waveguide and an end effector. In various embodiments, the membranes mayonly be placed at the antinodes while, in other embodiments, severalmembranes may be positioned in a region surrounding an anti-node, forexample. In any event, the membranes can further comprise one or moreapertures, slots, perforations, and/or openings 849 which can beconfigured to allow air to flow through the membranes 843, for example.In various embodiments, the membranes can comprise any suitable quantityof apertures, for example, such as one or more apertures, four or moreapertures, and/or ten or more apertures, for example. In at least oneembodiment, the apertures of one membrane 843, for example, can bealigned with the apertures of adjacent membranes 843. In variousembodiments, the outer portions 847 of membranes 843 can be adhered to,and/or otherwise suitably attached to, sheath 841 while the innerportions 845 of membranes 843 can be adhered to, and/or otherwisesuitably attached to, wave guide 846. In certain embodiments, the innerportions 845 can comprise a hole which can allow membranes 843 to beslid onto and positioned on wave guide 846. In various embodiments,membranes 843 can be comprised of a polymer material, for example,wherein the material can be thin enough to permit at least a portion ofthe membrane to move longitudinally while thick enough to withstandrepeated movements thereof.

In various circumstances, as outlined above, the piezoelectric elementsof a transducer positioned closer to a node may be required to performlarger quantities of work and may be subjected to higher temperaturesthan piezoelectric elements positioned further away from the node. Insuch circumstances, the piezoelectric elements closest to the node maydegrade, and lose their ability to perform a certain amount of work, ata faster rate than the piezoelectric elements positioned further awayfrom the node. When such degradation has occurred in the past, thetransducer was discarded. In various embodiments described herein, thetransducer can be disassembled after it has been used such that thepiezoelectric elements of the transducer can be rearranged. In at leastone embodiment, referring to FIG. 22A, a transducer 914 can comprisepiezoelectric elements 932 a, 932 b, 932 c, and 932 d wherein, in atleast the arrangement illustrated in FIG. 22A, piezoelectric elements932 a are positioned closest to the node N and piezoelectric elements932 d are positioned closest to the antinodes AN. After transducer 914has been used, it may be likely that piezoelectric elements 932 a willhave degraded more than piezoelectric elements 932 b, 932 c, and 932 d.In certain embodiments, as a result, piezoelectric elements 932 a can beshuffled to the ends of the transducer stack and piezoelectric elements932 b, 932 c, and 932 d can be moved inwardly as illustrated in FIG.22B. Thereafter, in such embodiments, piezoelectric elements 932 b mayperform larger quantities of work than piezoelectric elements 932 awould have. After transducer 914 has been used once again, transducer914 can be disassembled such that piezoelectric elements 932 b can beshuffled to the ends of the stack, or furthest away from the node, andpiezoelectric elements 932 c, and 932 d can be moved inwardly, or closerto the node. While this particular sequence of reshuffling thepiezoelectric elements may be useful, any other suitable sequence may beused.

In various embodiments, further to the above, a transducer can beassembled utilizing several piezoelectric elements which have been usedmore than once or have undergone different duty cycles. In at least oneembodiment, referring to FIG. 23A, transducer 1014, for example, can beassembled using first piezoelectric elements 1032 a which have undergonea first amount of duty cycles, if any, second piezoelectric elements1032 b which have undergone a second amount of duty cycles, thirdpiezoelectric elements 1032 c which have undergone a third amount ofduty cycles, and fourth piezoelectric elements 1032 d which haveundergone a fourth amount of duty cycles. In at least one suchembodiment, the first amount of duty cycles can be zero, or at less thanthe second amount of duty cycles, the second amount of duty cycles canbe less than the third amount of duty cycles, and the third amount ofduty cycles can be less than the fourth amount of duty cycles. Incertain circumstances, as a result, the fourth piezoelectric elements1032 d may be more degraded, or less capable of producing work, than thethird piezoelectric elements 1032 c, the third piezoelectric elements1032 c can be more degraded than the second piezoelectric elements 1032b, and the second piezoelectric elements 1032 b can be more degradedthan the first piezoelectric elements 1032 a. In such embodiments, thepiezoelectric elements having less duty cycles can be positioned closerto a node such that the less-degraded piezoelectric elements can moreefficiently contribute to the standing wave of longitudinal vibrationsand generate greater quantities of work. Stated another way, further tothe above, the largest longitudinal displacements, or vibrations,produced by a transducer are generated by piezoelectric elementspositioned at or near a node of the standing wave, wherein theless-degraded piezoelectric elements positioned at or near the node canbetter capitalize on their position.

After a transducer assembled in accordance with above, such astransducer 1014, for example, has been used, each of the piezoelectricelements, i.e., elements 1032 a, 1032 b, 1032 c, and 1032 d, of thetransducer will have undergone additional duty cycles and may havebecome further degraded. In at least one embodiment, as a result, thepiezoelectric elements 1032 d, which have undergone the most duty cyclesat this point, can be removed from the transducer stack. The otherremaining piezoelectric elements, i.e., elements 1032 a, 1023 b, and1032 c can be shifted outwardly within the transducer stack, orrepositioned within the transducer stack such that they are positionedfurther away from the node. In at least one such embodiment, referringnow to FIG. 23B, new piezoelectric elements, such as elements 1032 e,for example, can be positioned at or nearest to the node. In variousembodiments, piezoelectric elements 1032 e may have undergone no dutycycles, or may have undergone less duty cycles than piezoelectricelements 1032 a, for example. In any event, the transducer can bereassembled and used once again. Thereafter, the transducer can bedisassembled once again and new, or at least less-used, piezoelectricelements can be inserted into the stack. Although the insertion of new,or at least less-used, elements into the transducer stack may typicallycorrespond with the removal of a corresponding quantity of piezoelectricelements from the transducer stack, embodiments are envisioned in whichnew elements can be added to the transducer stack, thereby increasingthe total quantity of piezoelectric elements within the stack.Furthermore, although pairs of new, or at least less-used, piezoelectricelements can be replaced within the transducer at a given time,embodiments are envisioned where only one piezoelectric element, or morethan two piezoelectric elements, are replaced at a given time.

In various alternative embodiments, further to the above, thepiezoelectric elements having more duty cycles within a transducer canbe positioned at or nearest to a node while the piezoelectric elementshaving fewer duty cycles can be positioned further away from the node.In certain embodiments, as the piezoelectric elements having fewer dutycycles may be positioned closer to the antinodes, such piezoelectricelements may be capable of leveling, or at least better leveling, thework produced by the piezoelectric elements. More particularly, asdiscussed in great detail above, the piezoelectric elements positionedcloser to the antinodes of a standing wave of vibrations may undergoless stress and strain and, thus, have less capacity to draw current andproduce work and, by having the new, or less-degraded, piezoelectricelements positioned near the antinodes, such piezoelectric elements maybe able to compensate for the lesser stress and strain and provide agreater quantity of work than older, or more-degraded, piezoelectricelements would have provided. Similarly, by using the older, ormore-degraded, piezoelectric elements closer to the node, such elementsmay produce a flatter work profile than new, or less-degraded,piezoelectric elements would have provided. In various embodiments, aflatter work profile can be produced which can be beneficial in variouscircumstances as outlined herein.

As discussed in great detail above, an ultrasonic instrument cancomprise a transducer, a wave guide, and an end effector, wherein thetransducer can be configured to produce vibrations which causes asystem, or assembly, comprising the transducer, the wave guide, and theend effector to vibrate at a resonant frequency. As also discussedabove, the resonant frequency of such an assembly may be affected byvarious mounting or connecting members, for example. In any event, theassembly may be designed to have a particular resonant frequency, suchas approximately 55,000 kHz, for example. Owing to various manufacturingdifferences, however, each assembly may have a slightly differentresonant frequency and, as a result, each assembly may be tested inorder to find its resonant frequency. If it is determined that thenatural frequency of the assembly needs to be adjusted, the end of thewave guide and/or end effector may be ground in order to adjust theirlength and, as a result, adjust the resonant frequency of the assembly.Although such an assembly process may be useful for its intendedpurpose, the process may be time consuming and/or may not provideadequate adjustability of the assembly. For example, in the event thattoo much length is ground off of a wave guide, for example, the waveguide must typically be thrown out and the adjustment process must berepeated with a new wave guide.

In various embodiments, referring now to FIG. 24, an ultrasonicinstrument can comprise a transducer 1114, a wave guide 1146, and an endeffector 1150 which can collectively comprise an assembly having aresonant frequency, wherein wave guide 1146 can be mounted to transducer1114 such that transducer 1114 can be adjusted relative to wave guide1146. More particularly, in at least one embodiment, transducer 1114 cancomprise a threaded aperture 1115 which can be configured to threadablyreceive a threaded end 1151 of wave guide 1146 such that wave guide 1146can be rotated relative to transducer 1114 in order to move wave guide1146 and end effector 1150 along axis 1199. For example, wave guide 1146can be rotated in a clockwise direction in order to move the distal end1152 of end effector 1150 distally with respect to, or away from,transducer 1114. Correspondingly, wave guide 1146 can be rotated in acounter-clockwise direction in order to move distal end 1152 of endeffector 1150 proximally, or toward, transducer 1114. In certainembodiments, threaded aperture 1115 can extend between the proximal endof end-bell 1120 and the distal end of fore-bell 1122. In variouscircumstances, as a result of the above, the length “L” betweentransducer 1114 and the distal tip 1152 of end effector 1150 can beadjusted in order to tune the resonant frequency of the assembly suchthat it matches a desired resonant frequency. In at least oneembodiment, length “L” can be adjusted such that the distal tip 1152 ofend effector 1150 is positioned at, or near, an antinode of the standingwave of longitudinal vibrations and/or such that the center of thetransducer stack of piezoelectric elements 1132 is positioned at, ornear, a node of the standing wave of longitudinal vibrations.

In any event, once wave guide 1146, end effector 1150, and transducer1114 have been suitably positioned relative to one another, wave guide1146 can be immovably affixed to transducer 1114, for example. In atleast one embodiment, wave guide 1146 can be welded to end-bell 1120and/or fore-bell 1122. In certain embodiments, although not illustrated,the assembly can further comprise a connector which can be configured tooperably and releasably couple wave guide 1146 to transducer 1114. In atleast one such embodiment, the assembly can further comprise one or morecompression collars which can be threadably engaged onto end-bell 1120and/or fore-bell 1122 so as to compress end-bell 1120 and/or fore-bell1122 against wave guide 1146 and create a friction fit therebetween. Insuch embodiments, the compression collars can be uncoupled from end-bell1120 and/or fore-bell 1122 such that the relative position of wave guide1146 and transducer 1114 can be adjusted once again. In variousembodiments, although not illustrated, an ultrasonic assembly cancomprise a transducer and a wave guide, and/or end effector, wherein atleast a portion of the wave guide can be press-fit into a hole withinthe transducer. In at least one such embodiment, the position of thewave guide within the transducer hole can be adjusted with sufficientaxial force applied thereto even though the wave guide may be immovablerelative to the transducer during the course of the ordinary operationof the surgical instrument.

In various embodiments, also not illustrated, an ultrasonic instrumentcan comprise a transducer having an aperture and, in addition, a waveguide, or end effector, configured to be inserted into the aperture,wherein a thermal interference fit can be created between the wave guideand the sidewalls of the transducer aperture, for example. Moreparticularly, in at least one such embodiment, the transducer apertureand the wave guide can be configured such that the wave guide cannot beinserted into the transducer aperture when the transducer and the waveguide are at the same temperature, or at least substantially the sametemperature, although the transducer can be heated such that theaperture expands, and/or the wave guide can be cooled such that itcontracts, so that the wave guide can be inserted into the transduceraperture. Owing to such temperature differences, sufficient clearancecan exist between the wave guide and the side walls of the transduceraperture such that the position of the wave guide relative to thetransducer can be adjusted. After the transducer has been sufficientlycooled, and/or after the wave guide has been sufficiently warmed, aninterference fit may exist between the wave guide and the sidewalls ofthe transducer aperture. Such an interference fit can be referred to asa thermal interference fit. In any event, if it is determined that theposition of the wave guide needs to be readjusted, the transducer can beheated and/or the wave guide can be cooled once again in order to permitthe wave guide to be moved relative to the transducer once again.

In various embodiments, the length and mass of an assembly comprising atransducer, wave guide, and/or end effector can dictate the resonantfrequency of the assembly. In various circumstances, the length of theassembly can be selected such that the resonant frequency of theassembly is within a range of frequencies that a voltage or currentsource can supply to the transducer. In certain embodiments, a giventransducer, wave guide, and/or end effector may be required to be usedtogether and, in the event that a different length wave guide ordifferent end effector is needed, a different surgical instrumentaltogether may be required. In various alternative embodiments,referring now to FIG. 25, a surgical instrument kit can comprise ahandpiece comprising a transducer and two or more wave guides and/or twoor more end effectors which can be assembled to the transducer in orderto allow a surgical instrument to be adapted to have various lengthsand/or have various uses. More particularly, in at least one embodiment,a kit can comprise a transducer 1214, an integral first wave guide 1246a and first end effector 1250 a, and an integral second wave guide 1246b and second end effector 1250 b, wherein, in at least one suchembodiment, a surgeon can selectively assemble the integral first waveguide 1246 a and first end effector 1250 a, and/or the integral secondwave guide 1246 b and second end effector 1250 b, to transducer 1214such that the surgical instrument can have different lengths, forexample. In various embodiments, the length and mass of the integralfirst wave guide 1246 a and end effector 1250 a can be such that, whenthey are attached to transducer 1214, the voltage and/or current sourcecan supply power to the transducer 1214 at a first resonant frequencyand, similarly, the length and mass of the integral second wave guide1246 b and end effector 1250 b can be such that, when they are attachedto transducer 1214, the voltage and/or current source can supply powerto the transducer 1214 at a second, or different, resonant frequency. Incertain embodiments, the first and second resonant frequencies can bethe same, or at least substantially the same. In various embodiments,the transducer 1214 can comprise a threaded aperture 1268 and the waveguides 1246 a and 1246 b can each comprise a threaded stud 1248 whichcan be threadably inserted into the threaded aperture 1268. In certainembodiments, integral wave guide 1246 a and end effector 1250 a cancomprise a first length which is an integer multiple of one-half of thewavelength of the standing wave of vibrations, i.e., (n*λ)/2, at theresonant frequency of the assembly. Similarly, in at least oneembodiment, the integral wave guide 1246 b and end effector 1250 b cancomprise a second length which is an integer multiple of one-half of thewavelength of the standing wave of vibrations at the resonant frequencyof the assembly, i.e., (m*λ)/2, wherein m can be less than n, forexample. In various embodiments, the lengths of the wave guides and endeffectors can be configured such that the tips 1252 a and 1252 b of theassemblies, and/or the threaded studs 1248, are positioned at or near anantinode of the standing wave of vibrations.

In various embodiments, further to the above, an ultrasonic instrumentmay comprise a transducer, a wave guide, and an end effector, whereinthe ultrasonic instrument may further comprise a housing at leastpartially surrounding the transducer and a sheath at least partiallysurrounding the wave guide and/or end effector. In at least oneembodiment, referring to FIG. 26, ultrasonic surgical instrument 1310can comprise a transducer 1314, a housing 1316 encompassing transducer1314, a wave guide 1346, a sheath 1341 encompassing wave guide 1346, andan end effector 1350. In certain embodiments, surgical instrument 1310can further comprise one or more stabilizing supports 1356 which can beconfigured to support wave guide 1346 and/or end effector 1350 withinsheath 1341. In at least one such embodiment, sheath 1341 can comprise ahandle portion and/or can be configured to be grasped, or gripped, by asurgeon such that the surgeon can accurately manipulate surgicalinstrument 1310 and, in particular, accurately manipulate distal end1352 of end effector 1350. In at least one embodiment, at least aportion of the outer surface of sheath 1341 can comprise a roughenedand/or textured surface. In certain embodiments, the outer surface ofsheath 1341 can comprise a round, or at least substantially round,cross-section having a diameter of approximately 5 millimeters,approximately 10 millimeters, approximately 15 millimeters, and/or adiameter between approximately 4 millimeters and approximately 16millimeters.

In any event, supports 1356 can be sufficiently rigid to transfer forcesbetween sheath 1341 and wave guide 1346 and yet can be sufficientlycompliant to permit relative movement between wave guide 1346 and sheath1341. In certain embodiments, supports 1356 can also dampen vibrationstransmitted between wave guide 1346 and sheath 1341, for example. Invarious embodiments, supports 1356 can be positioned at or near thenodes of the standing wave of longitudinal vibrations, although supports1356 can be positioned at any suitable location. Supports 1356positioned at or near the nodes of the longitudinal standing wave ofvibrations may undergo smaller displacements and, thus, smallervibrations may be transmitted to sheath 1341, for example. In any event,transducer housing 1316 can be mounted to sheath 1341 wherein, invarious embodiments, housing 1316 can be adhered to, fastened to, and/orotherwise suitably affixed to sheath 1341. In various embodiments,housing 1316 can be mounted to sheath 1341 such that housing 1316 is notin direct contact with transducer 1314. In at least one such embodiment,transducer 1314 and housing 1316 can move, or float, relative to oneanother. In at least one embodiment, referring again to FIG. 26,surgical instrument 1310 can further comprise one or more compliantsupports, such as support 1353, for example, positioned intermediatehousing 1316 and sheath 1341, wherein support 1353 can be configured todampen vibrations transmitted between sheath 1341 and housing 1316. Incertain embodiments, support 1353 can comprise an o-ring compressedbetween sheath 1341 and housing 1316. Owing to such an arrangement, inat least one embodiment, the connection between transducer housing 1316and sheath 1341 can occur at any suitable location along the length ofsurgical instrument 1310 with little or no regard to whether such alocation is at a node and/or antinode of the standing wave oflongitudinal vibrations.

In various embodiments, further to the above, a transducer housing, suchas transducer housing 1316, for example, can be comprised of a rigid, orat least substantially rigid material, such as plastic, for example. Incertain embodiments, a transducer housing can be sufficiently flexiblesuch that it can be deflected, or elastically deformed, between a firstconfiguration, in which the transducer housing does not contact, or atleast substantially contact, a transducer positioned therein, and asecond position in which the transducer housing contacts the transducer.In at least one embodiment, referring now to FIGS. 27-30, an ultrasonicsurgical instrument can comprise a transducer 1414, a transducer housing1416 at least partially surrounding transducer 1414, and a wave guide1446 which can be operably coupled with transducer 1414. Similar to theabove, although not illustrated in FIGS. 27-30, the surgical instrumentcan further comprise a sheath at least partially surrounding wave guide1446, wherein at least a portion of housing 1416 can be mounted to thesheath, for example. In certain embodiments, referring to FIG. 28, asurgeon, or other clinician, can grasp housing 1416 in order to apply agripping force thereto and deflect it inwardly toward transducer 1414such that housing 1416 can engage at least a portion of transducer 1414,such as a gripping portion. In such circumstances, the surgeon orclinician can hold transducer 1414 in position via housing 1416 whilethey mount wave guide 1446 to transducer 1414. More particularly, in atleast one embodiment, transducer 1414 can comprise a distal end, orgripping portion, 1422, for example, having one or more flat surfaces,or at least substantially flat surfaces, 1421 which can be easilygripped by the surgeon or clinician while a proximal end of wave guide1446 is threadably inserted into the transducer, as outlined above. Insuch circumstances, referring again to FIG. 28, the surgeon or clinicianmay be able to rotate, or torque, transducer 1414 in a first directionand/or rotate, or torque, wave guide 1446 in a second, or oppositedirection, until wave guide 1446 and transducer 1414 are suitablysecured together. In other various embodiments, a transducer maycomprise grippable features which can allow the surgeon to insert a waveguide into the transducer in an axial, or longitudinal, direction, forexample. In any event, in at least one embodiment, the gripping portion1422, for example, can be located at an anti-node of the standing waveof longitudinal vibrations.

In various embodiments, once the wave guide has been mounted to thetransducer, the surgeon or clinician can release housing 1416 such thathousing 1416 sufficiently expands and is no longer in contact withtransducer 1414. In various embodiments, the housing 1416 can besufficiently resilient such that it returns to its original shape. Owingto the above, in certain embodiments, the transducer housing may notcontact the transducer and, as a result, may not impede or affect thestanding wave of vibrations created by the transducer during use. In theevent that the surgeon or clinician seeks to detach wave guide 1446 fromtransducer 1414, they may grip housing 1416 once again and rotate, ortorque, the wave guide and transducer in opposite directions. In variousembodiments, although not illustrated, a portion of a handle cancomprise one or more inwardly extending interlocking features which,when the handle is compressed inwardly towards a transducer, can beconfigured to engage corresponding interlocking features on thetransducer. Such embodiments can provide a keyed arrangement which canfacilitate holding the transducer in position when a wave guide or endeffector is mounted thereto, for example. Although not illustrated,various alternative embodiments are envisioned in which a flexiblehousing is mounted to the transducer at least one location, but isflexible inwardly to connect a wave guide or end effector to thetransducer as outlined herein.

In various embodiments, as outlined above, the power produced by atransducer of an ultrasonic surgical instrument, and/or the magnitude ofthe vibrations produced by the transducer, can be proportional thevoltage potential applied across the piezoelectric elements of thetransducer, for example. While increasing the voltage applied to thepiezoelectric elements can increase the power output of the transducer,such a power increase can be met with an undesirable increase intemperatures as outlined above. In certain embodiments, referring now toFIG. 31, a surgical instrument can comprise a wave guide 1546, an endeffector 1550, a first transducer 1514 a, and a second transducer 1514b, wherein wave guide 1546 can be mounted to first transducer 1514 a,and wherein first transducer 1514 a can be mounted to second transducer1514 b. In at least one embodiment, similar to the above, one oftransducer 1514 a and transducer 1514 b can comprise a threadedaperture, such as aperture 1568, for example, and the other oftransducer 1514 a and transducer 1514 b can comprise a threaded post,such as post 1548, for example, wherein threaded post 1548 and threadedaperture 1568 can be configured to securely fasten first transducer 1514a and second transducer 1514 b together.

In various embodiments, further to the above, the power of an ultrasonicinstrument can be increased by the selective attachment of secondtransducer 1514 b to first transducer 1514 a, for example. In at leastone embodiment, a kit can be provided to a surgeon including a handle, afirst transducer, a second transducer, and a wave guide and/or endeffector, wherein, if the surgeon desires the surgical instrument tohave a first, or lower, power, the surgeon, or other clinician, caninsert the first transducer 1514 a into the handle and assemble thefirst transducer 1514 a to the wave guide and/or end effector withoutassembling the second transducer 1514 b to the instrument. In certainembodiments, the first transducer 1514 a may already be inserted intothe handle and may already be operably engaged with the wave guideand/or end effector when the surgeon or other clinician receives thekit. In either event, if the surgeon desires that the surgicalinstrument should have a second, or larger, power, the surgeon canselectively attach the second transducer 1514 b to the first transducer1514 a, wave guide, and/or end effector. Similar to the above, incertain embodiments, the second transducer 1514 b may already bepreassembled to the first transducer 1514 a when the surgeon or otherclinician receives the kit.

In various embodiments, further to the above, a kit for a surgicalinstrument can comprise more than two transducers. In at least oneembodiment, for example, the kit may comprise a first transducerconfigured to supply a first quantity of power, a second transducerconfigured to supply a second quantity of power, and a third transducerconfigured to supply a third quantity of power, for example. In certainembodiments, a kit may have more than three transducers and, in someembodiments, some of the transducers within the kit can be configured tosupply the same, or at least substantially the same, quantity of power.In any event, the surgeon or other clinician can select from theprovided transducers in order to arrive at a desired quantity of powerthat will be supplied to the surgical instrument. In at least one suchembodiment, more than two transducers can be assembled together in orderto deliver power to the wave guide. In various embodiments, referringagain to FIG. 31, the transducers can be affixed to one another in aseries arrangement wherein the total deliverable power of the surgicalinstrument can be determined by summing the deliverable power of eachtransducer.

In various embodiments, further to the above, an ultrasonic surgicalinstrument comprising two or more transducers operably coupled to a waveguide and/or end effector of the surgical instrument can be configuredsuch that the transducers produce standing waves of vibrations whichoverlap, or at least substantially overlap, with one another. In atleast one embodiment, a surgical instrument can comprise a firsttransducer which produces a first standing wave of vibrations within awave guide and, in addition, a second transducer which produces a secondstanding wave of vibrations within the wave guide, wherein the nodes andantinodes of the first and second standing waves of vibrations can becoincident, or at least nearly coincident with one another. In at leastone such embodiment, the first and second standing waves of vibrationscan supplement each other such that the displacements produced by thestanding waves are superimposed onto one another and have an additiveeffect.

In certain embodiments, referring now to FIG. 32, two or moretransducers can be mounted to a wave guide and/or end effector of anultrasonic surgical instrument in a parallel arrangement. Moreparticularly, in at least one embodiment, an ultrasonic surgicalinstrument can comprise a wave guide 1646, an end effector 1650, a firsttransducer 1614 a, and a second transducer 1614 b, wherein transducers1614 a and 1614 b can both be mounted to a common mounting portion ofwave guide 1646. In certain embodiments, similar to the above, thetransducers and the wave guide can comprise co-operating threadedapertures and posts which can be utilized to secure the transducers tothe wave guide. Also similar to the above, the standing waves oflongitudinal vibrations produced by transducers 1614 a and 1614 b cansupplement each other such that the displacements produced by thestanding waves are superimposed onto one another and have an additiveeffect. In various embodiments, although not illustrated, an ultrasonicsurgical instrument can comprise transducers which can be operablyengaged with a wave guide and/or end effector in both parallel andseries arrangements. For example, first and second transducers can bedirectly mounted to a wave guide in parallel with one another, wherein athird transducer can be mounted to the first transducer such that it isin series with the first transducer, and wherein a fourth transducer canbe mounted to the second transducer such that it is in series with thesecond transducer, for example.

In various embodiments, further to the above, the first and secondtransducers of a surgical instrument can be configured such that thecenter of each of the piezoelectric stacks of the first and secondtransducers are positioned at, or near, a node of the standing wave ofvibrations. In other various embodiments, the first and secondtransducers of a surgical instrument can be configured such that thecenter of the piezoelectric stack of the first transducer is positionedat, or near, a node and such that the center of the piezoelectric stackof the second transducer is positioned closer to an antinode. In suchembodiments, further to the above, the first piezoelectric stack may beable to contribute more work, and may generate more heat, than thesecond piezoelectric stack. In at least one such embodiment, as aresult, the piezoelectric elements within the first transducer can bedifferent than the piezoelectric elements within the second transducer.More particularly, the piezoelectric elements of the first transducer,i.e., the transducer positioned closer to a node, can be comprised of amaterial, or materials, which have a higher strain constant, forexample, than the materials of the piezoelectric elements of the secondtransducer. In various embodiments, the piezoelectric elements of thefirst transducer can be comprised of a material having a higher Currietemperature, for example, than the material of the piezoelectricelements of the second transducer. In certain embodiments, thepiezoelectric elements of the first transducer can comprisepiezoelectric elements which have undergone a higher, or lower, quantityof duty cycles than the piezoelectric elements of the second transducer.

In various embodiments, an ultrasonic surgical instrument can comprise awave guide and/or end effector, a first transducer, and a secondtransducer, wherein the first and second transducers can be operablyengaged with the wave guide and/or end effector as outlined above. In atleast one embodiment, the first transducer and the second transducer caneach be selectively actuatable. In at least one such embodiment, thesurgical instrument can comprise a handle which can comprise one or moreswitches which can be configured to selectively actuate the first andsecond transducers positioned therein. For example, a switch can bemoved from an off position to a first position in order to actuate thefirst transducer, to a second position to actuate the second transducer,and/or to a third position to actuate the first transducer and thesecond transducer. In certain other embodiments, a handle can comprise afirst switch configured to selectively actuate the first transducer and,in addition, a second switch configured to selectively actuate thesecond transducer. In such embodiments, the surgeon can select the powerto be supplied to the wave guide and/or end effector. In variousalternative embodiments, a surgical instrument can comprise three ormore transducers which can be selectively actuated.

In various embodiments, as outlined above, a transducer can comprise afore-bell, an end-bell, and one or more piezoelectric elementscompressed, or clamped, between the fore-bell and end-bell. Often, thefore-bell and/or end-bell can include a shaft configured to bepositioned within apertures in the piezoelectric elements in order toalign the piezoelectric elements with each other. Once the transducerhas been assembled, in various embodiments, the wave guide and/or endeffector can be operably mounted to the transducer. In various otherembodiments described herein, an ultrasonic surgical instrument cancomprise a wave guide, an end effector, and one or more piezoelectricelements which can be mounted directly to the wave guide and/or endeffector. In at least one embodiment, referring to FIG. 33, a surgicalinstrument can comprise an end effector 1750 and an integral alignmentpost, or shaft, 1722, wherein piezoelectric elements having aperturestherein can be aligned with post 1722 such that the piezoelectricelements can be slid along post 1722 until they abut shoulder 1746. Invarious embodiments, referring now to FIG. 34, an ultrasonic surgicalinstrument can comprise an end effector 1850, a wave guide 1846, andpiezoelectric elements 1832, wherein elements 1832 can be slid alongshaft 1822 until they are stacked against wave guide 1846. Thereafter,an end member, such as end member 1820, for example, can be engaged withalignment shaft 1822 and utilized to secure piezoelectric elements 1832between end member 1820 and wave guide 1846. In at least one suchembodiment, alignment shaft 1822 can comprise a threaded end and, inaddition, end member 1820 can comprise a threaded aperture, wherein thethreaded aperture can be configured to threadably receive the threadedend of alignment shaft 1822.

In various embodiments, as outlined above, a voltage potential may beapplied to the piezoelectric elements of a transducer to contract andexpand the piezoelectric elements and generate vibrations. As alsooutlined above, such a voltage potential may be cycled between twovalues, such as between minimum and maximum values, for example. Invarious embodiments, the piezoelectric elements can be poled such thatthe voltage potential can affect the piezoelectric elements. Moreparticularly, the piezoelectric elements can undergo a poling processsuch that a net electric, or magnetic, dipole is stored within eachpiezoelectric element, wherein the voltage potential can interact withthe magnetic dipole and cause the piezoelectric element to vibrate.During a poling process, electrodes can be applied to the opposite sidesof a piezoelectric element such that a large electric field can beapplied across the piezoelectric element in order to arrange the domainswithin the piezoelectric material and create a net magnetic dipolewithin the piezoelectric element. In at least one embodiment, theelectrodes may be screen-printed onto the electrodes, wherein one ormore stencils can be aligned with the sides of the piezoelectricelement, and wherein a roller having conductive ink thereon can berolled across the stencil such that the conductive ink is selectivelyapplied to the piezoelectric element. In certain embodiments, a meshmaterial can be applied to the surface of the piezoelectric element,wherein the conductive ink can be pressed through the mesh, or woven,material which is not covered by a masking portion of the stencil.

In various embodiments, the electrodes utilized to pole thepiezoelectric elements, as outlined above, may be ground off of, and/orotherwise removed from, the piezoelectric elements such that a secondset of electrodes can be positioned intermediate the variouspiezoelectric elements of a transducer stack, wherein the second set ofelectrodes can generate the voltage potential used during the operationof the surgical instrument. In other various embodiments, a second setof electrodes can be applied to the piezoelectric elements utilizing aphysical vapor deposition process (PVD), wherein certain conductivematerials, such as metals, for example, can be evaporated in a lowpressure environment such that the conductive materials can be depositedonto the piezoelectric elements. In certain embodiments, a stencil, ormask, can be placed over the surfaces of the piezoelectric elements suchthat the conductive materials can be selectively deposited on thepiezoelectric elements.

In various embodiments, the electrodes utilized to pole thepiezoelectric elements can also be utilized to apply voltage potentialsto the piezoelectric elements during use. In at least one embodiment,the electrodes can be pad-printed onto the piezoelectric elements. In atleast one such embodiment, a conductive ink can be placed, or poured,onto a printing plate, wherein the surface of the ink can become tackyafter being exposed to air, for example. Thereafter, a transfer pad canbe pressed onto the ink such that the tacky portion of the ink adheresto transfer pad, the transfer pad can be positioned over a piezoelectricelement, and the transfer pad can be pressed onto the piezoelectricelement such that the ink adheres to the piezoelectric element. In suchembodiments, the printing plate can have various reliefs or contourswhich can define the areas of the printing plate which can store theconductive ink and, correspondingly, can define the respective areas onthe piezoelectric element in which the conductive ink will be applied.In various embodiments, the conductive ink can comprise a fluid, silver,and/or carbon, for example.

In various embodiments, further to the above, one or more electrodes canbe adhered to a piezoelectric element. In at least one embodiment,referring now to FIG. 35, a transducer can comprise one or morepiezoelectric elements 1932, wherein each piezoelectric element 1932 cancomprise a core, or disc, 1931, a positive electrode 1934, and anegative electrode 1936, for example. In at least one such embodiment,the positive electrode 1934 and/or the negative electrode 1936 can beadhered to the core 1931 utilizing a conductive adhesive. In use, as aresult, a voltage source can be operably coupled to the positiveelectrode 1934 and negative electrode 1936 such that a voltage potentialcan be created between the positive and negative electrodes, as outlinedabove. When the piezoelectric elements 1932 are assembled into atransducer stack, such as transducer stack 1914 (FIG. 36), for example,the piezoelectric elements 1932 can be arranged such that their positiveand/or negative electrodes are aligned with one another. For example,the negative electrode 1936 of piezoelectric element 1932 a can bepositioned against the negative electrode 1936 of piezoelectric element1932 b and, similarly, the positive electrode 1934 of piezoelectricelement 1932 b can be positioned against the positive electrode 1934 ofpiezoelectric element 1932 c, for example. Owing to contact betweenadjacent negative electrodes 1936, and/or owing to contact betweenadjacent positive electrodes 1934, the polarization of one of thenegative electrodes 1934, or positive electrodes 1936, may polarize anadjacent electrode.

In various embodiments, further to the above, each electrode cancomprise a body, which is adhered to piezoelectric element core 1931,and a tab, or portion, 1935 which can be configured to extend outwardlyfrom the electrode body and/or core 1931. In at least one suchembodiment, the piezoelectric element core 1931 of a piezoelectricelement can comprise an outer profile, wherein tabs, or portions, 1935can extend outwardly with respect to the outer profile of core 1931. Incertain embodiments, the tabs 1935 of adjacent piezoelectric elements1932 can be connected to one another. In at least one such embodiment,conductive clips, connectors, and/or connecting electrodes, for example,can be utilized to couple the tabs 1935 of adjacent piezoelectricelements 1932 such that the adjacent negative electrodes 1936, oradjacent positive electrodes 1934, can be in electrical communicationwith one another and have the same, or an at least substantiallysimilar, voltage potential. In at least one embodiment, a clip 1933 canconnect adjacent tabs 1935, wherein, in at least one embodiment, clip1933 can comprise a spring which can bias the clip from an openconfiguration into a closed configuration, for example. In certainembodiments, as described in greater detail further below, the cores1931, for example, of various piezoelectric elements can comprisealignment features which can be configured to assure that adjacentpiezoelectric elements can be assembled to each other in only one way,or a limited number of ways. In at least one such embodiment, thealignment features can be configured such that the tabs 1935 of theelectrodes are aligned, or at least substantially aligned, with oneanother when the alignment features of piezoelectric elements arealigned, or at least substantially aligned, with one another.

In various embodiments, referring now to FIGS. 37 and 38, a transducerstack 2014 can comprise a plurality of piezoelectric elements, such aselements 2032, for example, wherein each element 2032 can comprise anegative electrode 2034 and a positive electrode 2036. In certainembodiments, the transducer stack 2014 can further comprise one or morefirst connecting electrodes 2033 a which can operably connect aplurality of negative electrodes 2034 and, in addition, one or moresecond connecting electrodes 2033 b which can operably connect aplurality of positive electrodes 2036. More particularly, in at leastone embodiment, first connecting electrode 2033 a can be connected tothe tabs 2035 associated with negative electrodes 2034 in order topolarize each of the negative electrodes 2034 with the same, or at leastsubstantially the same, voltage potential and, in addition, secondconnecting electrode 2033 b can be connected to the tabs 2035 associatedwith the positive electrodes 2036 in order to polarize each of thepositive electrodes 2036 with the same, or at least substantially thesame, voltage potential. In various embodiments, the connectingelectrodes can comprise a brass or copper strip or material, forexample, wherein first connecting electrode 2033 a can be welded orsoldered to negative electrodes 2034 and, similarly, second connectingelectrode 2033 b can be welded or soldered to positive electrodes 2036.In some embodiments, the connecting electrodes can comprise insulatedwires, and/or any other suitable conductor. In certain embodiments,although not illustrated, the connecting electrodes can comprise one ormore clips or clamp elements which can be operably engaged with the tabs2035, for example. In any event, further to the above, the firstconnecting electrode 2033 a can be operably coupled with the negativeterminal of a battery 2029, and/or any other suitable power source, andthe second connecting electrode 2033 b can be operably coupled with thepositive terminal of the battery 2029, for example.

In various embodiments, referring to FIG. 39, the connecting electrodes2133 of a transducer stack 2114 can be positioned radially outwardlywith respect to the outside diameter (OD), or outer profile, of thepiezoelectric elements 2132. In various circumstances, various radialgaps can exist between the outside diameter (OD), or outer profile, ofthe piezoelectric elements 2132 and the transducer housing 2116 in orderto accommodate the connecting electrodes 2133. Such gaps, however, canrepresent lost power capacity of the piezoelectric elements. Moreparticularly, as discussed above, piezoelectric elements having largerdiameters, for example, have the capacity for producing largerquantities of work and, as the above-described gaps can represent a lossin the diameter, or size, of the piezoelectric elements, the gaps canreduce the power capacity of the piezoelectric elements. In certaincircumstances, however, some amount of gap, G, between the piezoelectricelements 2132 and the transducer housing 2116 may be desired in order toaccommodate the radial expansion, or Poisson's expansion, of thepiezoelectric elements 2132, especially when the piezoelectric elementsare subjected to longitudinal contraction.

In various embodiments, now referring to FIGS. 40 and 41, a transducerstack 2214 can comprise a plurality of piezoelectric elements 2232,positive polarizing electrodes 2236 and/or negative polarizingelectrodes 2234 positioned intermediate the piezoelectric elements 2232,and one or more connecting electrodes 2213 operably connecting thenegative electrodes 2234 and/or operably connecting the positiveelectrodes 2236. In at least one embodiment, referring to FIG. 41, eachpiezoelectric element 2232 can comprise an outside diameter, or outerprofile, and one or more grooves, notches, or slots, 2239 therein,wherein notches 2239 can be configured to have a connecting electrode2213 positioned therein. More particularly, in at least one embodiment,each notch 2239 can be sized and configured to receive a connectingelectrode 2213 such that there is a clearance fit between the connectingelectrode 2213 and the sidewalls of the notches 2239, for example. In atleast one such embodiment, each notch 2239 can have a width which iswider than the width “W” of a connecting electrode 2213 and a depthwhich is deeper than the height “L” of a connecting electrode 2213, forexample. In at least one embodiment, the width W can be approximately 2mm and the height L can be approximately 0.6 mm. In various embodiments,connecting electrodes 2213 and notches 2239 can be configured such thatthe connecting electrodes 2213 do not extend above, or outwardly withrespect to, the outer profile of the piezoelectric elements 2232. In anyevent, owing to notches 2239, referring to FIG. 41, the largest outerdiameter (OD=2r+2L), or outer profile, of the piezoelectric elements2232 can be larger than the largest outer diameter (OD=2r), or outerprofile, of the piezoelectric elements 2132 and, as a result,piezoelectric elements 2232 may be capable of generating more power thanpiezoelectric elements 2132, for example. In certain embodiments, thediameter of piezoelectric elements 2232 (OD=2r+2L) can have a diameterof approximately 8 mm, approximately 10 mm, approximately 12 mm,approximately 14 mm, and/or approximately 16 mm, for example, wherein,in certain embodiments, such piezoelectric elements can provide a powerincrease between approximately 13% and approximately 53%, for example,as compared to piezoelectric elements 2132.

In various embodiments, further to the above, the connecting electrodes2213 of transducer stack 2214, for example, can operably connect one ormore negative polarizing electrodes 2234 and/or one or more positivepolarizing electrodes 2236 with a power source. For example, referringagain to FIG. 40, a connecting electrode 2213 can connect a firstpositive electrode 2236 and a second positive electrode 2236 with thepositive terminal of a battery, for example, wherein the connectingelectrode 2213 can comprise a bridge which spans, and is not operablyengaged with, a negative electrode 2234 positioned intermediate thefirst and second positive electrodes 2236. On the other side of thetransducer stack, for example, another connecting electrode 2213 canoperably connect the second positive electrode 2236 with a thirdpositive electrode 2236, wherein, similar to the above, the connectingelectrode 2213 can comprise a bridge which spans, and is not operablyengaged with, another negative electrode 2234 positioned intermediatethe second and third positive electrodes 2236. In various embodiments,such a pattern can be repeated in order to operably connect all of thepositive electrodes 2236 within transducer stack 2214 with one anotherand the positive terminal of a power source. As can be seen in FIG. 41,the piezoelectric elements 2232 can comprise notches 2239 on theopposite sides thereof in order to accommodate the arrangement ofconnecting electrodes described above, although other arrangements arepossible. Similar to the above, a connecting electrode can be configuredto connect a first negative electrode 2234 and a second negativeelectrode 2234 with the negative terminal of a battery, for example,wherein the connecting electrode 2213 can comprise a bridge which spans,and is not operably engaged with, a positive electrode 2236 positionedintermediate the first and second negative electrodes 2234. On the otherside of the transducer stack, for example, another connecting electrode2213 can operably connect the second negative electrode 2234 with athird negative electrode 2234, wherein, similar to the above, theconnecting electrode 2213 can comprise a bridge which spans, and is notoperably engaged with, another positive electrode 2236 positionedintermediate the second and third negative electrodes 2234.

In various embodiments, referring now to FIGS. 42 and 43, a transducerstack 2314 can comprise a plurality of piezoelectric elements 2332,positive electrodes 2336 and/or negative electrodes 2334 positionedintermediate the piezoelectric elements 2332, and one or more connectingelectrodes 2313 operably connecting the negative electrodes 2334 and/oroperably connecting the positive electrodes 2336. In at least oneembodiment, piezoelectric elements 2332 can comprise one or more flatsurfaces 2339 which can be configured to accommodate connectingelectrodes 2313 yet permit the average diameter of the piezoelectricelements 2332 to be increased as compared to the average diameters ofpiezoelectric elements 2132. More particularly, referring to FIG. 43,the diameters of various circular portions of each piezoelectric element2332, i.e., the portions intermediate flats 2339, can be increased suchthat the outer diameter of the piezoelectric element (OD=2r+2L) is thesame distance, or at least substantially the same distance, as adiameter defined by connecting electrodes 2313. In at least one suchembodiment, such intermediate portions can add to the overall size, orarea, of each piezoelectric element 2332 and, thus, add to the quantityof work that the piezoelectric elements can produce. In certainembodiments, similar to the above, various portions of piezoelectricelements 2332 can have a diameter of approximately 8 mm, approximately10 mm, approximately 12 mm, approximately 14 mm, and/or approximately 16mm, for example, wherein, in certain embodiments, such piezoelectricelements can provide a power increase between approximately 11% andapproximately 42%, for example, as compared to piezoelectric elements2132. In various embodiments, flats 2339 can be machined into thepiezoelectric element, for example.

In various embodiments, as outlined above, the piezoelectric elements ofa transducer can undergo a poling process such that a net dipole can beestablished within the piezoelectric element. In at least oneembodiment, such a net dipole can comprise a positive charge (+), anegative charge (−), and a net dipole moment vector defined between thenegative charge and the positive charge. In certain embodiments,referring now to FIGS. 44 and 45, the positive charge (+) of apiezoelectric element, such as piezoelectric elements 2432, for example,can be positioned on one side of the piezoelectric element while thenegative charge (−) can be positioned on the opposite side of thepiezoelectric element. In at least one such embodiment, eachpiezoelectric element 2432 can comprise one or more indicia which canindicate the direction of the net dipole moment vector. For example,piezoelectric elements 2432 can comprise an arrow 2433 formed on theside thereof, wherein the arrow 2433 can point in a direction toward thepositive charge and away from the negative charge. In at least oneembodiment, arrow 2433 can be ground, pressed, and/or etched, forexample, into the side of the piezoelectric element while, in otherembodiments, arrow 2433 can be integrally formed with the piezoelectricelement when the piezoelectric element is manufactured, for example. Invarious embodiments, the arrow 2433 can extend from and/or be recessedwithin the side of the piezoelectric element. In certain embodiments,the arrows 2433 can be painted and/or otherwise suitably applied to thepiezoelectric elements. In any event, piezoelectric elements having atleast one indicium can allow a person assembling a transducer to readilyrecognize the polarity of the piezoelectric elements and, as a result,quickly and reliably, arrange the piezoelectric elements such that theirpoles are properly aligned with one another. In various embodiments, theindicia of a first piezoelectric element can be aligned with the indiciaof a second piezoelectric element in order to align the dipole momentvector of the first element with the dipole moment vector of the secondelement.

In addition to or in lieu of the above, piezoelectric elements cancomprise one or more indexing features which can be configured to assurethat adjacent piezoelectric elements are properly aligned with oneanother. For example, referring again to FIGS. 44 and 45, piezoelectricelements 2432 can comprise one or more recesses, or grooves, 2437 andone or more projections 2439, wherein projections 2439 can be configuredto be seated within recesses 2437 when piezoelectric elements 2432 areproperly aligned with one another. More particularly, in at least oneembodiment, projections 2439 can be seated within recesses 2437 onlywhen piezoelectric elements are aligned along a common axis 2499 and thepolarity of the piezoelectric elements 2432 are aligned such thepositive charge (+) on one side of an element is aligned with thepositive charge of an adjacent element and/or the negative charge (−) onthe other side of the element is aligned with the negative charge ofadjacent element. Absent a suitable alignment between the indexingfeatures, referring to FIG. 45, the piezoelectric elements 2432 may notbe properly seated with one another and a person, or machine, assemblinga transducer may be able to quickly detect the misalignment. In variousembodiments, various piezoelectric elements, such as elements 2432, forexample, can be configured such they can be assembled in pairs and suchthat the outwardly-facing surfaces of the piezoelectric elements areflat and parallel with one another, or at least substantially flat andsubstantially parallel with one another, wherein, referring again toFIG. 44, the negative charges of the elements can be adjacent to theflat surfaces, and wherein various mated pairs of the piezoelectricelements can be stacked on top of one another with the flat surfaces andnegative charges aligned with each other. In at least one suchembodiment, the net dipole moment vectors of the piezoelectric elementscan be perpendicular, or at least substantially perpendicular, withrespect to the outwardly-facing flat surfaces of the piezoelectricelements

In various circumstances, as outlined above, the piezoelectric elementsof a transducer may, for whatever reason, lose their ability, or atleast a portion of their ability, to generate sufficient vibrations tovibrate the end effector of an ultrasonic surgical instrument. Once atransducer has exceeded its useful life, the transducer is oftendisposed of. In various circumstances, the piezoelectric elements ofsuch transducers, for example, may be at least partially comprised oflead and/or other certain materials. In various embodiments describedherein, a transducer, and/or surgical instrument, may comprise means inwhich to encapsulate or contain the piezoelectric elements of thetransducer when it is desired to dispose of the transducer. In variousembodiments, referring now to FIG. 46, a transducer assembly, such astransducer assembly 2514, for example, can comprise a transducer stack2518 comprising an end-bell 2520, a fore-bell 2522, one or morepiezoelectric elements 2532 positioned intermediate end-bell 2520 andfore-bell 2522, for example, and an enclosure which is configured to atleast partially enclose the transducer stack 2518. In at least oneembodiment, the enclosure may surround the entire piezoelectric elementstack 2518 such that only a portion of the fore-bell 2522 extendsthrough the enclosure in order to allow a wave guide and/or end effectorto be operably engaged with the transducer stack 2518.

In various embodiments, further to the above, transducer assembly 2514can comprise an enclosure 2561 which can have a first compartment 2563and a second compartment 2565, wherein the transducer stack 2518 can bepositioned within the first compartment 2563 and a material 2567 can bepositioned within the second compartment 2565. Before disposing of thetransducer assembly 2514, in at least one embodiment, the secondcompartment 2565 can be ruptured such that the material 2567 can flowfrom the first compartment 2563 into the second compartment 2565 and atleast partially surround transducer stack 2518, as illustrated in FIG.47. In at least one such embodiment, referring to FIG. 46, a sidewall2569 can be configured to separate the first compartment 2563 and thesecond compartment 2565, wherein the sidewall 2569 can be configured torupture in at least one location. In various embodiments, sidewall 2569,for example, can comprise one or more score marks, or weak points, forexample, which can determine the locations in which the sidewall 2569may be most likely to rupture. In certain embodiments, the enclosure2561 can be configured such that a person can use their hand to squeezethe enclosure 2561 and burst the sidewall 2569 separating firstcompartment 2563 and second compartment 1265. In various embodiments,the enclosure 2561 can be configured such the material 2567 cannotthereafter escape, or at least substantially escape, from enclosure2561. In at least one such embodiment, the enclosure 2561 can be sealed,or at least substantially sealed, to fore-bell 2522, for example, suchthat the material 2567 cannot flow, or at least substantially flow,between enclosure 2561 and the portion of fore-bell 2522 which extendsout of enclosure 2561.

In various embodiments, referring now to FIG. 48, a transducer assembly2614 can comprise an enclosure 2661 comprising at least one valve whichcan be opened to place a first compartment 2665 in fluid communicationwith a second compartment 2663. More particularly, in at least oneembodiment, the enclosure 2661 can comprise a sidewall 2669 and one ormore valves 2671, for example, which can be selectively opened to permitmaterial 2667 to flow from first compartment 2665 into secondcompartment 2663. In at least one such embodiment, especially inembodiments where material 2667 is a fluid, valves 2671 can beconfigured to pop open when subjected to sufficient fluid pressuregenerated within material 2667 when the enclosure 2661 is compressed. Invarious embodiments, material 2667 can be fluidic when it is positionedwithin the first compartment 2665 and when it initially surroundstransducer stack 2618. In certain embodiments, however, the material2667 can be configured to harden after it has entered into firstcompartment 2665. In at least one such embodiment, first compartment2665 can be air-tight and, when the material 2667 enters into the secondcompartment 2663, the material 2667 can be exposed to air, for example,which can cause it harden. In any event, whether or not the materialremains fluidic or hardens, the material can encapsulate, or at leastpartially encapsulate, certain materials within the transducer stack tofurther reduce the possibility of such materials from escaping from theenclosure.

The devices disclosed herein can be designed to be disposed of after asingle use, or they can be designed to be used multiple times. In eithercase, however, the device can be reconditioned for reuse after at leastone use. Reconditioning can include any combination of the steps ofdisassembly of the device, followed by cleaning or replacement ofparticular pieces, and subsequent reassembly. In particular, the devicecan be disassembled, and any number of the particular pieces or parts ofthe device can be selectively replaced or removed in any combination.Upon cleaning and/or replacement of particular parts, the device can bereassembled for subsequent use either at a reconditioning facility, orby a surgical team immediately prior to a surgical procedure. Thoseskilled in the art will appreciate that reconditioning of a device canutilize a variety of techniques for disassembly, cleaning/replacement,and reassembly. Use of such techniques, and the resulting reconditioneddevice, are all within the scope of the present application.

Preferably, the various embodiments described herein will be processedbefore surgery. First, a new or used instrument is obtained and ifnecessary cleaned. The instrument can then be sterilized. In onesterilization technique, the instrument is placed in a closed and sealedcontainer, such as a plastic or TYVEK bag. The container and instrumentare then placed in a field of radiation that can penetrate thecontainer, such as gamma radiation, x-rays, or high-energy electrons.The radiation kills bacteria on the instrument and in the container. Thesterilized instrument can then be stored in the sterile container. Thesealed container keeps the instrument sterile until it is opened in themedical facility. Sterilization can also be done by any number of waysknown to those skilled in the art including beta or gamma radiation,ethylene oxide, and/or steam.

In various embodiments, an ultrasonic surgical instrument can besupplied to a surgeon with a wave guide and/or end effector alreadyoperably coupled with a transducer of the surgical instrument. In atleast one such embodiment, the surgeon, or other clinician, can removethe ultrasonic surgical instrument from a sterilized package, plug theultrasonic instrument into a generator, as outlined above, and use theultrasonic instrument during a surgical procedure. Such a system canobviate the need for a surgeon, or other clinician, to assemble a waveguide and/or end effector to the ultrasonic surgical instrument. Afterthe ultrasonic surgical instrument has been used, the surgeon, or otherclinician, can place the ultrasonic instrument into a sealable package,wherein the package can be transported to a sterilization facility. Atthe sterilization facility, the ultrasonic instrument can bedisinfected, wherein any expended parts can be discarded and replacedwhile any reusable parts can be sterilized and used once again.Thereafter, the ultrasonic instrument can be reassembled, tested, placedinto a sterile package, and/or sterilized after being placed into apackage. Once sterilized, the reprocessed ultrasonic surgical instrumentcan be used once again.

Although various embodiments have been described herein, manymodifications and variations to those embodiments may be implemented.For example, different types of end effectors may be employed. Also,where materials are disclosed for certain components, other materialsmay be used. The foregoing description and following claims are intendedto cover all such modification and variations.

Any patent, publication, or other disclosure material, in whole or inpart, that is said to be incorporated by reference herein isincorporated herein only to the extent that the incorporated materialsdoes not conflict with existing definitions, statements, or otherdisclosure material set forth in this disclosure. As such, and to theextent necessary, the disclosure as explicitly set forth hereinsupersedes any conflicting material incorporated herein by reference.Any material, or portion thereof, that is said to be incorporated byreference herein, but which conflicts with existing definitions,statements, or other disclosure material set forth herein will only beincorporated to the extent that no conflict arises between thatincorporated material and the existing disclosure material.

1. A transducer for a surgical instrument, said transducer comprising: afirst polarizing electrode; a first piezoelectric element, comprising: afirst outer profile; and a first notch in said first outer profile; asecond piezoelectric element, comprising: a second outer profile; and asecond notch in said second outer profile; a second polarizing electrodepositioned intermediate said first piezoelectric element and said secondpiezoelectric element; a third polarizing electrode; a first connectingelectrode configured to operably connect said first polarizing electrodeand said third polarizing electrode with a power source, wherein saidfirst connecting electrode is positioned within said first notch; and asecond connecting electrode configured to operably connect said secondpolarizing electrode with the power source, wherein said secondconnecting electrode is positioned within said second notch.
 2. Thetransducer of claim 1, wherein said first connecting electrode isrecessed within said first notch such that it does not extend above saidfirst outer profile of said first piezoelectric element, and whereinsaid second connecting electrode is recessed within said second notchsuch that it does not extend above said second outer profile of saidsecond piezoelectric element.
 3. The transducer of claim 1, wherein saidfirst piezoelectric element and said second piezoelectric element arepositioned along a longitudinal axis, and wherein said first notch andsaid second notch are positioned on opposite sides of said longitudinalaxis.
 4. The transducer of claim 1, wherein said first outer profilecomprises a circular profile, and wherein said first notch comprises aflat surface in said circular profile.
 5. The transducer of claim 1,wherein first notch comprises a groove in said first outer profile.
 6. Atransducer for a surgical instrument, said transducer comprising: afirst piezoelectric element, comprising: a first body; a first netdipole polarity defining a first dipole moment vector; and a firstindicia indicating the direction of said first dipole moment vector; anda second piezoelectric element, comprising: a second body; a second netdipole polarity defining a second dipole moment vector; and a secondindicia indicating the direction of said second dipole moment vector,wherein said first indicia is configured to be aligned with said secondindicia to align said first dipole moment vector with said second dipolemoment vector.
 7. The transducer of claim 6, wherein said first indiciais integrally formed with said first body of said first piezoelectricelement.
 8. The transducer of claim 6, wherein said first body comprisesa first surface and a second surface, and wherein said first dipolevector is substantially perpendicular to said first surface and saidsecond surface.
 9. The transducer of claim 6, wherein said first netdipole polarity comprises a positive charge and a negative charge,wherein said first dipole moment vector points from said negative chargeto said positive charge, and wherein said second net dipole polaritycomprises a positive charge and a negative charge and said second dipolemoment vector points from said negative charge to said positive charge.10. The transducer of claim 6, wherein said first net dipole polaritycomprises a positive charge and a negative charge, wherein said secondnet dipole polarity comprises a positive charge and a negative charge,wherein said first body and said second body are configured such thatsaid first indicia cannot be aligned with said second indicia unlesssaid positive charges and said negative charges of said first and secondnet dipoles are arranged in a predetermined arrangement.
 11. A surgicalinstrument, comprising: a transducer configured to produce vibrations,said transducer comprising: a first piezoelectric element, wherein saidfirst piezoelectric element has been subjected to a first amount of dutycycles; and a second piezoelectric element, wherein said secondpiezoelectric element has been subjected to a second amount of dutycycles, wherein said second amount of duty cycles is greater than saidfirst amount of duty cycles; and an end effector operably coupled tosaid transducer, wherein said transducer is configured to produce astanding wave of vibrations in said transducer and said end effector,wherein said standing wave comprises a node and an anti-node, andwherein said first piezoelectric element is positioned closer to saidnode than said second piezoelectric element.
 12. The surgical instrumentof claim 11, wherein said node comprises a point within at least one ofsaid transducer and said end effector in which a maximum stress iscreated, and wherein said anti-node comprises a point within at leastone of said transducer and said end effector in which a minimum stressis created.
 13. The surgical instrument of claim 11, wherein said firstpiezoelectric element is positioned at said node.
 14. The surgicalinstrument of claim 11, wherein said transducer is operably engageablewith a power source configured to apply a voltage potential to saidfirst piezoelectric element and a voltage potential to said secondpiezoelectric element, wherein said first piezoelectric element isconfigured to draw a first current and said second piezoelectric elementis configured to draw a second current, and wherein said first currentis larger than said second current.
 15. The surgical instrument of claim11, wherein said transducer further comprises a third piezoelectricelement, wherein said third piezoelectric element has been subjected toa third amount of duty cycles, wherein said third amount of duty cyclesis greater than said second amount of duty cycles.
 16. A surgicalinstrument, comprising: a transducer configured to produce vibrations,said transducer comprising: a first piezoelectric element having a firstthickness; and a second piezoelectric element having a second thickness,wherein said second thickness is greater than said first thickness; andan end effector operably coupled to said transducer, wherein saidtransducer is configured to produce a standing wave of vibrations insaid transducer and said end effector, wherein said standing wavecomprises a node and an anti-node, and wherein said first piezoelectricelement is positioned closer to said node than said second piezoelectricelement.
 17. The surgical instrument of claim 16, wherein said nodecomprises a point within at least one of said transducer and said endeffector in which a maximum stress is created, and wherein saidanti-node comprises a point within at least one of said transducer andsaid end effector in which a minimum stress is created.
 18. The surgicalinstrument of claim 16, wherein said first piezoelectric element ispositioned at said node.
 19. The surgical instrument of claim 16,wherein said transducer is operably engageable with a power sourceconfigured to apply a voltage potential to said first piezoelectricelement and a voltage potential to said second piezoelectric element,wherein said first piezoelectric element is configured to draw a firstcurrent and said second piezoelectric element is configured to draw asecond current, and wherein the magnitude of said first current issubstantially the same as the magnitude of said second current.
 20. Amethod of assembling a transducer for a surgical instrument, whereinsaid transducer is configured to produce a standing wave of vibrationshaving a node and an anti-node, said method comprising the steps of:selecting a first piezoelectric element having a first materialproperty, wherein said first piezoelectric element is configured to drawa first current when a voltage potential is applied thereto; selecting asecond piezoelectric element having a second material property, whereinsaid second piezoelectric element is configured to draw a second currentwhen a voltage potential is applied thereto; and arranging said firstpiezoelectric element and said second piezoelectric element relative tosaid node such that the difference between the magnitude of said firstcurrent and the magnitude of said second current is minimized.
 21. Themethod of claim 20, wherein said first material property is a firstthickness of said first piezoelectric element, wherein said secondmaterial property is a second thickness of said second piezoelectricelement, and wherein said second thickness is larger than said firstthickness.
 22. The method of claim 20, wherein said first materialproperty is a first dielectric constant, wherein said second materialproperty is a second dielectric constant, and wherein said firstdielectric constant is larger than said second dielectric constant. 23.The method of claim 20, wherein said first material property is a firstvoltage sensitivity, wherein said second material property is a secondvoltage sensitivity, and wherein said second voltage sensitivity islarger than said first voltage sensitivity.
 24. A surgical instrument,comprising: a transducer configured to produce vibrations, saidtransducer comprising: a first piezoelectric element comprised of afirst material having a first strain constant; and a secondpiezoelectric element comprised of a second material having a secondstrain constant, wherein said second strain constant is greater thansaid first strain constant; and an end effector operably coupled to saidtransducer, wherein said transducer is configured to produce a standingwave of vibrations in said transducer and said end effector, whereinsaid standing wave comprises a node and an anti-node, and wherein saidfirst piezoelectric element is positioned closer to said node than saidfirst piezoelectric element.
 25. The surgical instrument of claim 24,wherein said node comprises a point within at least one of saidtransducer and said end effector in which a maximum stress is created,and wherein said anti-node comprises a point within at least one of saidtransducer and said end effector in which a minimum stress is created.26. The surgical instrument of claim 24, wherein said firstpiezoelectric element is positioned at said node.
 27. The surgicalinstrument of claim 24, wherein said transducer is operably engageablewith a power source configured to apply a voltage potential to saidfirst piezoelectric element and a voltage potential to said secondpiezoelectric element, wherein said first piezoelectric element isconfigured to draw a first current and said second piezoelectric elementis configured to draw a second current, and wherein the magnitude ofsaid first current is substantially equal to the magnitude of saidsecond current.
 28. The surgical instrument of claim 24, wherein saidtransducer further comprises a third piezoelectric element, wherein saidthird piezoelectric element is comprised of a third material having athird strain constant, wherein said third strain constant is greaterthan said second strain constant, and wherein said second piezoelectricelement is closer to said node than said third piezoelectric element.